Greetings

I've been working on an optional subclass feature and I would like some opinions to bounce it of. I know it is strong but our setting kinda allow for such power. Still, I'd like to know your opinions.

Be gentle, it's my first homebrew ... Text is as follow :

Les Dagues

Remember to add your bonus to hit after your attack roll and whatever bonus damage after your damage roll.

~~ Pool of Daggers ~~

• Dagger +1 with +1d4 Cold Damage
• Dagger of Warning

~~ Notes ~~

As an action, you use your grafted powers to manifest blades in your free hands and make an attack. Those are replicas of daggers you know or have been attuned with, along with their magical, finesse and thrown properties. They stay manifested as long as you do not dismiss them.

It has a normal range of 60 feet with no long range, dealing force damage equal to 1d4 plus your ability modifier. At 5th level it deals 2d4, at 11th level it deals 3d4, at 17th level it deals 4d4. 

The blade vanishes immediately after it hits or misses its target, and it leaves no mark on its target if it deals damage. If the dagger has an additional effect that needs it to be left on the target, you can choose to leave it there, otherwise you make it vanish and reappear in your free hand as a free action.

After you attack with the blade, you can make a melee or ranged weapon attack with a second psychic blade as a bonus action on the same turn. You do not apply your ability modifier to your off-hand attack's damage.

Learning of the intricacies of a dagger in order to be able to manifest it using your psychic powers requires that you spend an hour studying it, as if you were taking the time to get attunement to it, during which a copy of the blade is manifested on the off-hand. It takes a single attunement slot to join up with your previously attuned daggers pool, requiring a single attunement slot for any and all daggers you would ever get attuned with. However, once you are attuned with one, that attunement slot is permanently tied to “Les Dagues”. As such and even when you appear to be unarmed or have already dismissed a dagger, you still get the full benefits of the last dagger you manifested, as if it was still in your palm.
For the sake of simplicity "Les Dagues" does not mechanically requires attunement. You get to select which of your dagger will take up the attunement slot, for the passive effect. For example keeping attuned to a Dagger of Warning would grant Advantage on initiative rolls. You will need to swap them during combat if you juggle between multiple daggers.

You will still need to familiarize with the actual daggers of your Pool of Daggers each day during your morning meditation (at dawn), in order to fully remember the details of each of the daggers it includes.
If you do not have access to a dagger from your Pool of Daggers, you roll a D4. On a 1, this dagger is no longer part of your Pool of Daggers until you have access to it again. If you do not have any daggers, you can still manifest the basic dagger of this feature.

Deux dagues affûtées apparaissent soudainement dans les mains d’Hyrkali, comme sortant du néant. Aucune fioriture, seulement de l’efficacité. Dans un mouvement harmonieux, ses mains décrivirent deux arcs de cercle vifs, de fins traits d’ombre traversèrent l’espace jusqu’à leur cible. Aucun bruit, aucune marque, aucune preuve de blessure à l’impact sinon le corps de l’assassin qui s’effondra au fond de la ruelle, inconscient. Nul ne saurait dire si les dagues avaient ou non quitté les mains d’Hyrkali. De toute façon, plus personne ne pourrait en témoigner. Les ombres ne parlent pas et c’est tout ce qu’il y avait désormais dans cette allée…

Two sharpened knives suddenly appears in Hyrkali's hand, as if coming out of the void. No flourish, only pure efficiency. In a single harmonious movement, her hands drew two keen arcs, thin blades of shadow travelling space to their target. No sound, no marks, no proofs of wounds at the point of impact other then the body of the assassin collapsing down the alley, lifeless. No one could tell if the blades ever left Hyrkali's hands. In any event, no one would speak of it. Shadows never talk and that is all what was left in this backstreet.

Proficiency with a dagger allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Now excuse the flavor text in French - I haven't taken time to translate it... I translated the best I could. The name of feature is French because yeah... why not. :D
Should I ever go and publish, I'll finetune it to proper English...

So!
Basically based on the Soulknife Psychic Blade feature, it is a damage tool that scales, like cantrip does. The goal is to provide a means of weapon, grafted to the wielder, at the cost of a permanent attunement slot, which you can swap and embed daggers in. A bit like a pact of the blade weapon... And yeah, I do have some Royal Arms feeling from Final Fantasy - wasn't what I had in mind but a friend told me and I kinda was caught offguard by the similarities. :P

We are obviously heavy on the homebrew in our campaign...

My current issue is : What/why would I ever want something other then a Dagger of Warning in that attunement slot, prior to a fight? During a fight, I can see the usefulness of swapping to a Dagger of Venom, a Blindsight Dagger, a Keen Dagger, or a Flame Tongue variation... but basically anytime you aren't in combat... are there anything other Dagger that might beneficial to being used for its "passive" bonuses? Blindsight is useful, true, but I could always use an action to swap prior to initiative (if not surprised)...

What are your thoughts on the item in general? Wording is a bit lengthy too...
It's homebrewed as an item that I'm currently editing, adjusting the bonus on my character sheet as needed, adding custom action to my character. Maybe there's an easier way to do it but since the Pool of Daggers is that of my character... That'd need to be noted elsewhere probably.

Thanks for your time in reading and commenting this.