The class feature is deliberately written to prevent this sort of interaction. Note that they're not Light weapons, so the Nick property would be meaningless on them.
You're right. That's really dumb. Blades made of psychic energy are not lighter than actual daggers? That's just.. wtf man.
So the maximum attacks you can ever have with a SoulKnife Rogue is 3? Do they at least benefit from the "Dueling" Fighting style?
Genuinely curious. With the exception of throwing builds, why would anyone play this subclass? Actually, just using 2 returning daggers would result in more damage with a throwing build. So I seriously don't understand this design choice to not have the Psychic Blades be Light weapons.
Genuinely curious. With the exception of throwing builds, why would anyone play this subclass?
Because Psychic Blades isn't the only feature they get. Maybe some people find the other features interesting and fun. Maybe combat isn't their only priority.
Actually, just using 2 returning daggers would result in more damage with a throwing build.
Where are you going to get two returning daggers at 3rd level?
So I seriously don't understand this design choice to not have the Psychic Blades be Light weapons.
To stop this kind of cheese.
You're already getting their Mastery Property for free, few things resist psychic damage, their throwing range is insanely high for a melee weapon, you're always armed even when you appear to be carrying no weapons, your murder weapons leave no trace, you can fix botched Stealth or Deception rolls with your Psionic Energy Dice, and you can set up telepathic voice chats with your entire group that last hours at a time for free. And that's just their 3rd level features.
Most of what you mentioned is usually not relevant in Combat. We're talking about Combat.
Soulknife is completely pointless for Melee builds at all levels below 17th level. It's especially pointless if you try to pair it with 5 levels in Barbarian, Monk, Ranger, Paladin, or Fighter. You'd actually get more melee damage output from 2 completely normal daggers because then you'd get 4 attacks every round.
Against an enemy with 16 AC with 20 DEX and using Sneak Attack (assuming Advantage on all attacks):
It's just worse for no reason. And that's not even considering that you could also just use Scimitars and 4 attacks or the fact that the Psychic Blades get out-scaled by Magic Weapons. If you could add a +2 from the Dueling Fighting Style it makes it better (39.26 DPR) but it's still not great. Especially if we picked Barbarian and not Fighter because more attacks means more benefit from the Rage damage bonus.
Now what if they had the Light Property (they are made of magic ffs) and could work alongside a Nick weapon like a regular dagger? Then you get this:
Which is considerably better that the non-Dueling-abuse damage output. It's still worse than using Scimitars though (which is 42.88 DPR) but at least now it competes with regular daggers. It's nowhere near "Cheese" though.
Oh and for Throwing? Yes the Psychic Blades have great range compared to all other thrown weapons. But when that range isn't needed they get out-damaged by just having 1 or more Returning Daggers or just carrying around a couple of normal daggers to throw. These things only weight 1 lb. and cost 2 GP so it's not that hard.
After looking at the math the only thing the Psychic Blades really have going for them is that they do Psychic damage, which is either amazing or irrelevant depending on what you're fighting.
You clearly like the subclass. So why argue against wanting it to be stronger?!? Making its signature weapons Light doesn't make the subclass broken, it just brings it in line with what other options available. "Magic Psychic Energy Blades" should be better that a weapon you can buy for 2 GP. Who tf designed this?
It's fine for a Subclass to not be combat oriented. But tell me what do you see in the official art for the subclass? A rogue wielding two Psychic Blades. What's the name of the subclass? Soulknife, emphasis on the knife part.
The signature feature of the subclass is its ability to let you create and fight with Psychic Blades. It's not the ONLY feature, but it's the selling point. And it was fine until they added the Nick property.
Now, the signature feature of the subclass is out-performed by a common weapon that costs 2 GP. A kitchen knife does more damage than your magically created psychic energy blades. That's not good design man. Come on. It doesn't make any sense both in-universe and logically.
"Hey come play this subclass you get cool energy weapons" ---- 2 session later---> "I'd be better off with kitchen knives"
HOW TF ARE YOU OK WITH THAT? Especially if you like this subclass.
Open your eyes and read what I'm saying. I'm literally saying the thing you like SHOULD be better.
Op. You'll have to homebrew it to be able to do what you want to do. Below is what I did so that it works. And to the person who said that it wouldn't work cause the Psychic Blades aren't light weapons? They actually do because the Dual Wielder feat specifically says the extra attack can be made with any weapon that doesn't have the two-handed property. So yes, they could pull it off with the Psychic Blades, with my homebrew below of course.
"The blade vanishes immediately after it hits or misses its target, and it leaves no mark if it deals damage. If the Soulknife has extra attacks from multiclassing or from spells such as Haste, then the Soulknife can manifest another shimmering blade to use for those extra attacks.
After you attack with the blade on your turn, you can make another melee or ranged attack with a second psychic blade as a Bonus Action on the same turn. The damage die of this bonus attack is 1d4 instead of 1d6."
I basically added the bolded text and removed the text about the other hand needing to be free. I didn't change anything else about the subclass.
It's fine for a Subclass to not be combat oriented. But tell me what do you see in the official art for the subclass? A rogue wielding two Psychic Blades. What's the name of the subclass? Soulknife, emphasis on the knife part.
The signature feature of the subclass is its ability to let you create and fight with Psychic Blades. It's not the ONLY feature, but it's the selling point. And it was fine until they added the Nick property.
Now, the signature feature of the subclass is out-performed by a common weapon that costs 2 GP. A kitchen knife does more damage than your magically created psychic energy blades. That's not good design man. Come on. It doesn't make any sense both in-universe and logically.
"Hey come play this subclass you get cool energy weapons" ---- 2 session later---> "I'd be better off with kitchen knives"
HOW TF ARE YOU OK WITH THAT? Especially if you like this subclass.
Open your eyes and read what I'm saying. I'm literally saying the thing you like SHOULD be better.
The Soulknife has many great and fun things to do outside of combat. If your focus is combat, however, then why are you playing a rogue to begin with? You keep talking about DPR and stuff. Well, if DPR is your goal, you're playing the wrong class. If you still want to play a rogue because you like it, even though their DPR is outclassed by most (or all) other classes, then you can use the same argument to play a Soulknife.
Also, you keep talking about multiclassing. Which is fine, but not everyone will. A lot of people don't. So maybe the question should be "Why would you multiclass as a Soulknife?" as opposed to "Why would you play a Soulknife?"
Most of what you mentioned is usually not relevant in Combat. We're talking about Combat.
Having an infinite supply of magical 60' range throwing knives is very relevant to combat. And if you don't care about the stealth features, why are you even looking at Rogues? Genuine question. While Rogues aren't bad at combat, it's not their focus. Or at the very least, why not look at a Rogue subclass that's more obviously combat-oriented, like the Assassin or Swashbuckler?
Soulknife is completely pointless for Melee builds at all levels below 17th level. It's especially pointless if you try to pair it with 5 levels in Barbarian, Monk, Ranger, Paladin, or Fighter. You'd actually get more melee damage output from 2 completely normal daggers because then you'd get 4 attacks every round.
Against an enemy with 16 AC with 20 DEX and using Sneak Attack (assuming Advantage on all attacks):
Daggers don't have 60 foot range, and they don't have Vex, so where are you getting Advantage on all attacks from? If you're going to pull some buff from one of your party members out of thin air for the dagger scenario, why aren't you doing that for the psychic blades? If you're assuming Dual Wielder for the dagger build, where is feat the Soul Knife would take instead?
But when that range isn't needed they get out-damaged by just having 1 or more Returning Daggers or just carrying around a couple of normal daggers to throw. These things only weight 1 lb. and cost 2 GP so it's not that hard.
When is that range ever not needed? The higher level you get, the more dangerous it is to stand close to monsters. And those daggers aren't magical, are they? Who's handing out Returning Daggers into your campaign? How are you so sure you'll get one?
You clearly like the subclass. So why argue against wanting it to be stronger?!?
Because it doesn't need to be stronger? It's good to have trade-offs. That's what keeps a game interesting. You might as well ask "well why wouldn't you want the Rogue to also have 9th level spells and Three Extra Attacks and heavy armor proficiency? Wouldn't that be great?"
I think the discussion here is about comparing Vex with Nick.
"assuming Advantage on all attacks", how exactly are you going to get this? Your advantage from being hidden is only going to work on the first attack, not all of them.
On the other hand, the Vex property does allow you to have advantage on all attacks. You do the first attack with Advantage (while hidden for example), and if you hit, your second attack will also have Advantage thanks to the Vex property.
This means, with Vex, you can do all 3 attacks with Advantage, plus if the last attack hits, you will have Advantage on the next turn as well, getting into an "advantage loop" with all your attacks done with advantage, every round.
Meanwhile, with the Nick property you will have advantage only on the first attack. It's a comparison between: 3 attacks with advantage vs 4 attacks, 1 with advantage, 3 without.
I'd take the advantage on a Soulknife anyday, because it makes it easier to apply Sneak attack damage.
Yes, it is bad design. It apparently was designed to stop you from equaling a dagger user. Because that would be cheese, you have to actually be worse than the dagger wielder for the sub class not to be cheesy. Oh and then just wait for when magic weapons start coming into play.
edit to add and it wont by the rules work with things like true strike, booming blade etc.
Yes, it is bad design. It apparently was designed to stop you from equaling a dagger user. Because that would be cheese, you have to actually be worse than the dagger wielder for the sub class not to be cheesy. Oh and then just wait for when magic weapons start coming into play.
edit to add and it wont by the rules work with things like true strike, booming blade etc.
It is a fun idea executed terribly.
Pretty much agree. The concept is awesome. But the execution is terrible. Which is why I homebrewed the changes I added above so that the combat part makes sense for my table.
If you're trying to play a combat focused rogue you're asking for disappointment. It's like trying to focus on social interactions as a fighter. You could probably figure it out and be useful but you'll never be as good as other classes that are builtfor it. Rogues are utility and skill. And the Soulknife should absolutely be focused on passing skill checks. They are literally built for it. There's a Soulknife in my group I don't think I can remember her failing a skill check. Some battles were dropped from hard to easy before it even started because she went in first and sabotaged everything. That's what rogues are built for. Not combat damage.
You can only use one weapon mastery per turn anyway so you couldn't do what you are trying to do without homebrewing that you could use more than one weapon mastery per turn. Apologies if someone already said this.
I'm not sure where you got that from but it's not true. You can use weapon masteries with every attack made. Like rogue attacking with a shortsword (vex) to gain advantage for a scimitar (nick) attack in the same turn without using a bonus action for dual wielding every turn.
Sounds like you are a F5/R5 so yes you might be able to get the homebrew item +2 dagger of throwing but realize it is a homebrew item ( I know - I homebrewed it) but as others have said if your focus is on melee damage/dpr then the very first question is why rogue at all? There is a reason why rogues only get 1 attack a round - the are not meant to be a true martial but more a melee capable skill monkey much the same as bards ( melee and magic capable but…) . If you wanted to be a psi Dpr you have psychic warriors. If you wanted to be dagger thrower you have the throwing fighting style. I know, you MC with fighter to get the 2 attacks to enlarge your sneak attack chances and now you want your psychic daggers to give you all the benefits of real daggers (which they aren’t) so you can be a psionic dagger throwing fighter with 4 attacks not the 3 you actually get with this build. Yes you can homebrew it but RAW no it’s not possible.
The people who keep saying why are you playing a rogue, taking this sub class if you want dpr are missing the point. And missing it so big its baffling.
You have a sub class that is named after its key feature, creating a psychic blade. Does the sub class have great skill enhancing abilities as well, sure, but given how good rogues are its kind of just an extra layer of icing on the cake. But you want your key ability the one your sub class is named after to remain useful through the campaign, not trap out as soon as magic weapons are introduced and then maybe have like 1-2 levels of usefulness at level 9 until you get rare weapons. so sure, let assassins be better at damage than the psychic blade as they are a more damage focused sub class, just design the psychic blade in a way that you keep using it once magic weapons are introduced as whether you are an assassin or a psychic blade whatever magic weapons are in your campaign you will have access to.
As an aside rogues should have pretty dang solid single target damage. Not as good as a fighter sure, but not super far off. It should be worse than most other pure martials but better than casters and 1/2 casters. Its too bad they keep screwing that up.
Most of what you mentioned is usually not relevant in Combat. We're talking about Combat.
Soulknife is completely pointless for Melee builds at all levels below 17th level. It's especially pointless if you try to pair it with 5 levels in Barbarian, Monk, Ranger, Paladin, or Fighter. You'd actually get more melee damage output from 2 completely normal daggers because then you'd get 4 attacks every round.
Against an enemy with 16 AC with 20 DEX and using Sneak Attack (assuming Advantage on all attacks):
It's just worse for no reason. And that's not even considering that you could also just use Scimitars and 4 attacks or the fact that the Psychic Blades get out-scaled by Magic Weapons. If you could add a +2 from the Dueling Fighting Style it makes it better (39.26 DPR) but it's still not great. Especially if we picked Barbarian and not Fighter because more attacks means more benefit from the Rage damage bonus.
Now what if they had the Light Property (they are made of magic ffs) and could work alongside a Nick weapon like a regular dagger? Then you get this:
Which is considerably better that the non-Dueling-abuse damage output. It's still worse than using Scimitars though (which is 42.88 DPR) but at least now it competes with regular daggers. It's nowhere near "Cheese" though.
Oh and for Throwing? Yes the Psychic Blades have great range compared to all other thrown weapons. But when that range isn't needed they get out-damaged by just having 1 or more Returning Daggers or just carrying around a couple of normal daggers to throw. These things only weight 1 lb. and cost 2 GP so it's not that hard.
After looking at the math the only thing the Psychic Blades really have going for them is that they do Psychic damage, which is either amazing or irrelevant depending on what you're fighting.
You clearly like the subclass. So why argue against wanting it to be stronger?!? Making its signature weapons Light doesn't make the subclass broken, it just brings it in line with what other options available. "Magic Psychic Energy Blades" should be better that a weapon you can buy for 2 GP. Who tf designed this?
You want to know what's sad about your math?
A Rogue 10 with Psychic Blades is dealing an average 33.5 with two attacks, assuming both hit, Evasion, Reliable Talent, a second Subclass Feature, and a third ASI.
Yeah 5 levels for one extra attack probably isn't worth it imo, but it may be since you now have 2 level 3 sub class abilities, though a soul knifes level 9 is very solid. But 1 level for a fighting styles might be, sure you only have 3 attacks with nick but you give up 1/2 d6 in sneak attack and gain quite a bit. Where soul knife falls down is magic weapons. At most levels you will just be better off with a basic magic weapon, and when vicious weapons hit the field, a nick build there starts blowing the soul knife psychic blades out of the water. A soul knifes accuracy will be much higher at least, but 3 extra potential 2d6s a round is hard to compete with.
I had hoped when the DMG came out there would be answers for this, like a bracer that lets you bind magic weapon effects that you attune to with your psychic blades or something. Monks at least can just use monk weapons but its unfortunate their fists only get +1-+3 enchants. Sucks for the monks who wanted to go that route though.
Honestly I don't like vicious and how lame it makes sneak attack look, especially with a nick build. A level 11 fighter going nick is doing a extra 10d6 damage a round(assuming all hits) which is a rogues end sneak attack damage at 19. A rogue can at least sort of catch up and do a extra 6d6 if they go nick.
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Stop replying to this thread already, ffs
The class feature is deliberately written to prevent this sort of interaction. Note that they're not Light weapons, so the Nick property would be meaningless on them.
The Forum Infestation (TM)
You're right. That's really dumb. Blades made of psychic energy are not lighter than actual daggers? That's just.. wtf man.
So the maximum attacks you can ever have with a SoulKnife Rogue is 3? Do they at least benefit from the "Dueling" Fighting style?
Genuinely curious. With the exception of throwing builds, why would anyone play this subclass? Actually, just using 2 returning daggers would result in more damage with a throwing build. So I seriously don't understand this design choice to not have the Psychic Blades be Light weapons.
Because Psychic Blades isn't the only feature they get. Maybe some people find the other features interesting and fun. Maybe combat isn't their only priority.
Where are you going to get two returning daggers at 3rd level?
To stop this kind of cheese.
You're already getting their Mastery Property for free, few things resist psychic damage, their throwing range is insanely high for a melee weapon, you're always armed even when you appear to be carrying no weapons, your murder weapons leave no trace, you can fix botched Stealth or Deception rolls with your Psionic Energy Dice, and you can set up telepathic voice chats with your entire group that last hours at a time for free. And that's just their 3rd level features.
The Forum Infestation (TM)
Most of what you mentioned is usually not relevant in Combat. We're talking about Combat.
Soulknife is completely pointless for Melee builds at all levels below 17th level. It's especially pointless if you try to pair it with 5 levels in Barbarian, Monk, Ranger, Paladin, or Fighter. You'd actually get more melee damage output from 2 completely normal daggers because then you'd get 4 attacks every round.
Against an enemy with 16 AC with 20 DEX and using Sneak Attack (assuming Advantage on all attacks):
It's just worse for no reason. And that's not even considering that you could also just use Scimitars and 4 attacks or the fact that the Psychic Blades get out-scaled by Magic Weapons. If you could add a +2 from the Dueling Fighting Style it makes it better (39.26 DPR) but it's still not great. Especially if we picked Barbarian and not Fighter because more attacks means more benefit from the Rage damage bonus.
Now what if they had the Light Property (they are made of magic ffs) and could work alongside a Nick weapon like a regular dagger? Then you get this:
Which is considerably better that the non-Dueling-abuse damage output. It's still worse than using Scimitars though (which is 42.88 DPR) but at least now it competes with regular daggers. It's nowhere near "Cheese" though.
Oh and for Throwing? Yes the Psychic Blades have great range compared to all other thrown weapons. But when that range isn't needed they get out-damaged by just having 1 or more Returning Daggers or just carrying around a couple of normal daggers to throw. These things only weight 1 lb. and cost 2 GP so it's not that hard.
After looking at the math the only thing the Psychic Blades really have going for them is that they do Psychic damage, which is either amazing or irrelevant depending on what you're fighting.
You clearly like the subclass. So why argue against wanting it to be stronger?!? Making its signature weapons Light doesn't make the subclass broken, it just brings it in line with what other options available. "Magic Psychic Energy Blades" should be better that a weapon you can buy for 2 GP. Who tf designed this?
It's fine for a Subclass to not be combat oriented. But tell me what do you see in the official art for the subclass? A rogue wielding two Psychic Blades. What's the name of the subclass? Soulknife, emphasis on the knife part.
The signature feature of the subclass is its ability to let you create and fight with Psychic Blades. It's not the ONLY feature, but it's the selling point. And it was fine until they added the Nick property.
Now, the signature feature of the subclass is out-performed by a common weapon that costs 2 GP. A kitchen knife does more damage than your magically created psychic energy blades. That's not good design man. Come on. It doesn't make any sense both in-universe and logically.
"Hey come play this subclass you get cool energy weapons" ---- 2 session later---> "I'd be better off with kitchen knives"
HOW TF ARE YOU OK WITH THAT? Especially if you like this subclass.
Open your eyes and read what I'm saying. I'm literally saying the thing you like SHOULD be better.
Op. You'll have to homebrew it to be able to do what you want to do. Below is what I did so that it works. And to the person who said that it wouldn't work cause the Psychic Blades aren't light weapons? They actually do because the Dual Wielder feat specifically says the extra attack can be made with any weapon that doesn't have the two-handed property. So yes, they could pull it off with the Psychic Blades, with my homebrew below of course.
"The blade vanishes immediately after it hits or misses its target, and it leaves no mark if it deals damage. If the Soulknife has extra attacks from multiclassing or from spells such as Haste, then the Soulknife can manifest another shimmering blade to use for those extra attacks.
After you attack with the blade on your turn, you can make another melee or ranged attack with a second psychic blade as a Bonus Action on the same turn. The damage die of this bonus attack is 1d4 instead of 1d6."
I basically added the bolded text and removed the text about the other hand needing to be free. I didn't change anything else about the subclass.
The Soulknife has many great and fun things to do outside of combat. If your focus is combat, however, then why are you playing a rogue to begin with? You keep talking about DPR and stuff. Well, if DPR is your goal, you're playing the wrong class. If you still want to play a rogue because you like it, even though their DPR is outclassed by most (or all) other classes, then you can use the same argument to play a Soulknife.
Also, you keep talking about multiclassing. Which is fine, but not everyone will. A lot of people don't. So maybe the question should be "Why would you multiclass as a Soulknife?" as opposed to "Why would you play a Soulknife?"
Having an infinite supply of magical 60' range throwing knives is very relevant to combat. And if you don't care about the stealth features, why are you even looking at Rogues? Genuine question. While Rogues aren't bad at combat, it's not their focus. Or at the very least, why not look at a Rogue subclass that's more obviously combat-oriented, like the Assassin or Swashbuckler?
Daggers don't have 60 foot range, and they don't have Vex, so where are you getting Advantage on all attacks from? If you're going to pull some buff from one of your party members out of thin air for the dagger scenario, why aren't you doing that for the psychic blades? If you're assuming Dual Wielder for the dagger build, where is feat the Soul Knife would take instead?
When is that range ever not needed? The higher level you get, the more dangerous it is to stand close to monsters. And those daggers aren't magical, are they? Who's handing out Returning Daggers into your campaign? How are you so sure you'll get one?
Because it doesn't need to be stronger? It's good to have trade-offs. That's what keeps a game interesting. You might as well ask "well why wouldn't you want the Rogue to also have 9th level spells and Three Extra Attacks and heavy armor proficiency? Wouldn't that be great?"
The Forum Infestation (TM)
I think the discussion here is about comparing Vex with Nick.
"assuming Advantage on all attacks", how exactly are you going to get this? Your advantage from being hidden is only going to work on the first attack, not all of them.
On the other hand, the Vex property does allow you to have advantage on all attacks. You do the first attack with Advantage (while hidden for example), and if you hit, your second attack will also have Advantage thanks to the Vex property.
This means, with Vex, you can do all 3 attacks with Advantage, plus if the last attack hits, you will have Advantage on the next turn as well, getting into an "advantage loop" with all your attacks done with advantage, every round.
Meanwhile, with the Nick property you will have advantage only on the first attack. It's a comparison between: 3 attacks with advantage vs 4 attacks, 1 with advantage, 3 without.
I'd take the advantage on a Soulknife anyday, because it makes it easier to apply Sneak attack damage.
Yes, it is bad design. It apparently was designed to stop you from equaling a dagger user. Because that would be cheese, you have to actually be worse than the dagger wielder for the sub class not to be cheesy. Oh and then just wait for when magic weapons start coming into play.
edit to add and it wont by the rules work with things like true strike, booming blade etc.
It is a fun idea executed terribly.
Pretty much agree. The concept is awesome. But the execution is terrible. Which is why I homebrewed the changes I added above so that the combat part makes sense for my table.
If you're trying to play a combat focused rogue you're asking for disappointment. It's like trying to focus on social interactions as a fighter. You could probably figure it out and be useful but you'll never be as good as other classes that are builtfor it. Rogues are utility and skill. And the Soulknife should absolutely be focused on passing skill checks. They are literally built for it. There's a Soulknife in my group I don't think I can remember her failing a skill check. Some battles were dropped from hard to easy before it even started because she went in first and sabotaged everything. That's what rogues are built for. Not combat damage.
You can only use one weapon mastery per turn anyway so you couldn't do what you are trying to do without homebrewing that you could use more than one weapon mastery per turn. Apologies if someone already said this.
I'm not sure where you got that from but it's not true. You can use weapon masteries with every attack made. Like rogue attacking with a shortsword (vex) to gain advantage for a scimitar (nick) attack in the same turn without using a bonus action for dual wielding every turn.
Sounds like you are a F5/R5 so yes you might be able to get the homebrew item +2 dagger of throwing but realize it is a homebrew item ( I know - I homebrewed it) but as others have said if your focus is on melee damage/dpr then the very first question is why rogue at all? There is a reason why rogues only get 1 attack a round - the are not meant to be a true martial but more a melee capable skill monkey much the same as bards ( melee and magic capable but…) . If you wanted to be a psi Dpr you have psychic warriors. If you wanted to be dagger thrower you have the throwing fighting style. I know, you MC with fighter to get the 2 attacks to enlarge your sneak attack chances and now you want your psychic daggers to give you all the benefits of real daggers (which they aren’t) so you can be a psionic dagger throwing fighter with 4 attacks not the 3 you actually get with this build. Yes you can homebrew it but RAW no it’s not possible.
Wisea$$ DM and Player since 1979.
The people who keep saying why are you playing a rogue, taking this sub class if you want dpr are missing the point. And missing it so big its baffling.
You have a sub class that is named after its key feature, creating a psychic blade. Does the sub class have great skill enhancing abilities as well, sure, but given how good rogues are its kind of just an extra layer of icing on the cake. But you want your key ability the one your sub class is named after to remain useful through the campaign, not trap out as soon as magic weapons are introduced and then maybe have like 1-2 levels of usefulness at level 9 until you get rare weapons. so sure, let assassins be better at damage than the psychic blade as they are a more damage focused sub class, just design the psychic blade in a way that you keep using it once magic weapons are introduced as whether you are an assassin or a psychic blade whatever magic weapons are in your campaign you will have access to.
As an aside rogues should have pretty dang solid single target damage. Not as good as a fighter sure, but not super far off. It should be worse than most other pure martials but better than casters and 1/2 casters. Its too bad they keep screwing that up.
You want to know what's sad about your math?
A Rogue 10 with Psychic Blades is dealing an average 33.5 with two attacks, assuming both hit, Evasion, Reliable Talent, a second Subclass Feature, and a third ASI.
That's a lot to give up for only 0.3 DPR.
Yeah 5 levels for one extra attack probably isn't worth it imo, but it may be since you now have 2 level 3 sub class abilities, though a soul knifes level 9 is very solid. But 1 level for a fighting styles might be, sure you only have 3 attacks with nick but you give up 1/2 d6 in sneak attack and gain quite a bit. Where soul knife falls down is magic weapons. At most levels you will just be better off with a basic magic weapon, and when vicious weapons hit the field, a nick build there starts blowing the soul knife psychic blades out of the water. A soul knifes accuracy will be much higher at least, but 3 extra potential 2d6s a round is hard to compete with.
I had hoped when the DMG came out there would be answers for this, like a bracer that lets you bind magic weapon effects that you attune to with your psychic blades or something. Monks at least can just use monk weapons but its unfortunate their fists only get +1-+3 enchants. Sucks for the monks who wanted to go that route though.
Honestly I don't like vicious and how lame it makes sneak attack look, especially with a nick build. A level 11 fighter going nick is doing a extra 10d6 damage a round(assuming all hits) which is a rogues end sneak attack damage at 19. A rogue can at least sort of catch up and do a extra 6d6 if they go nick.