One of the biggest issues coming into the Monk class is expectations you can build Raizo out of Ninja Assassin, one of the Seven Deadly Venoms, or one of the sword wielding masters out of Crouching Tiger Hidden Dragon.  But then...you find out you have proficiency in simple weapons.  There is an option presented to you, the Kensei.  However, you sacrifice a huge number of flavor of other specializations just for the privilege of choosing a ranged martial weapon and a melee martial weapon.  If I read my history of D&D correctly, 4th edition had Monks terrorizing the board with ranged weapons.  They could float about the board with easy and pepper the enemies to death with bows.  However, the options added in Tasha's seems to be allowing for some of these options for Monks with the right build.  A character can now chose any weapon they have proficiency in and make it a Monk weapon.  My question here is, would taking the basic abilities provided by the Kensei and making them core to the Monk class really overpower the monk?  Given their Ki pools would remain the same, I feel it would simply add more options for them.

Raizo was not a monk, He may have used a form of mortial arts but he was very different. He's not something well represented in many games because he's a Ninja Assassin. Ninja usually used very different Weapons from what the Monk used.  There is also the issue that Raizo is basically inhuman And not truely representable by any class and is an unrealistic expectation in most games.  he does afterall make Beatrix from Kill Bill seem like a small school girl playing pretend.

Crouching Tiger Hidden Dragon as I recall actually revolves around a form of short sword. The Green Destiny Blade as I recall was something like a Jian which is within about 6 inches of what many would call a typical short sword in size.

So your actually not out of place with a Monk using a Version of a Short sword to do the basic sword fighting from Crouching Tiger HIdden Dragon. Though a fair bit of unarmed combat actually takes place in that movie that is not outside of the realm of the existing 5e monk except for running on air for long distances and balancing on flimsy treetops.

The 5 Venoms used almost no weapons at all and mostly specialized in different ways they used their bodies.  Some for defensive technique's that did have their weaknesses.  Some of their movement abilities however were out there even for the wire work stunts of Kung Fu movies and your not likely to find any version of D&D that takes it that far.  That's only found in a couple of more free form or Asian culture setting RPG's to my knowledge.

The Kensai doesn't actually reflect either your Sources of inspiration or your stories about what you heard might have been possible from 4e. And I would guess there was something wrong with the way it worked in 4e or it did not actually work that way or 5e likely would have been closer to that in ability.  So No. You don't actually gain anything significant by simply making it part of the Core Monk.  On top of that anything that the Kensai can do is simply an extension of what the Core Monk can already do. It's the one that actually makes the least alteration of any to the Style and capabilities of the Core Monk Class. It simply enhances them in a few ways with a somewhat narrow focus.

WADR Fateless,

Raizo can be represented in the game except for the classes lack of martial proficiency for some of his weapons.  The Shadow Arts Monk has quite a few Ninja like abilities.  The only thing he lacks is martial weapons so you couldn't use the whip like weapon that Raizo uses.  I think if you considered Raizo about 17th level or so it becomes more understandable how he tore everyone apart like they were paper.  After all, his shurken were probably doing d10+bonus each.  That actually might blow a 0 or 1st level target into bloody pieces.

I'll give you the crouching tiger, but I was actually picturing their sword to be more of a Rapier as it was clearly a finesse weapon.  Again, a martial weapon.

I'll give you the Deadly Venoms reference.  All I remember clearly out of that show was how they killed that poor guy with Toad style.

You kind of avoided the question I asked, would simply making the Kensei's abilities part of the Core Monk unbalance the Monk?

I don't see why you think monk should get Kensei features when you mention Dedicated Weapon from Tasha's, which allows a monk with a martial weapon.

If you want to play a monk that specializes in weapons, well that's exactly what a subclass is for. I don't think base monk needs Kensei features any more than I think base fighter needs Battlemaster features or base druid needs Circle of the Moon features. 

Also, you must be mistaken about 4e monks. Classes in 4e had special at-will powers that replaced the generic "Attack." Monk at-will powers all emphasized melee or close blast/burst effects. I suppose you could make basic ranged attacks with bows, but monks were no better than this than any other class (and definitely worse at it than something like a Ranger).

The Dedicated Weapon entry I saw said, "in which you are proficient".  That seemed to create a limit on the use of the ability.  It's still technically restricted to the monks simple weapons and fists initially unless you obtain sword abilities via race or otherwise.  Really encourages a lot of elf monks.

Or a dip in another class. Several can get you all martial weapons.

Quote from Malavian_Kripnar >>

WADR Fateless,

Raizo can be represented in the game except for the classes lack of martial proficiency for some of his weapons.  The Shadow Arts Monk has quite a few Ninja like abilities.  The only thing he lacks is martial weapons so you couldn't use the whip like weapon that Raizo uses.  I think if you considered Raizo about 17th level or so it becomes more understandable how he tore everyone apart like they were paper.  After all, his shurken were probably doing d10+bonus each.  That actually might blow a 0 or 1st level target into bloody pieces.

I'll give you the crouching tiger, but I was actually picturing their sword to be more of a Rapier as it was clearly a finesse weapon.  Again, a martial weapon.

I'll give you the Deadly Venoms reference.  All I remember clearly out of that show was how they killed that poor guy with Toad style.

You kind of avoided the question I asked, would simply making the Kensei's abilities part of the Core Monk unbalance the Monk?

 

 the Destiny Blade was not a finesse weapon an isn't as thin or long as rapiers. it was all about their fighting style that made it seem that way which is what the monk already does naturally through martial arts allowing any monk weapon to be able to use Dexterity as it's modifier regardless of the weapon actually being a finesse weapon.  Monks can actually wield some very blunt forceful simple weapons in a way that is very graceful and dextrous technically because of the inherent styles that martial arts encompasses.

I did answer it. Giving the Kensai's abilities to the base monk.. More than what it already is of course... It's actually pointless.  Because the kensai is just the most basic style boosted. But the monk doesn't need that boost to be balanced or effective.  The True Flavor of the monk is in it's Subclasses and that's a place where the Kensai sadly lacks a bit.  The Only thing holding Kensai up and making it truely Special right now is that it is a subclass so it is bringing it's qualities to the table in a special way by not all the other monks not having them. But a the same time if the other monks did have them they actually wouldn't be enhanced in any real way because they have too much other stuff that is fitting and thematic about them that either doesn't mix with the Way the Kensai amplifies things or just has outright enough other things going on with it that the Kensai's boosts would just be more things that the core monk never uses while playing those sub classes so people would complain and still want things changed or thing they need to be better worked to be more useful or things like that just as the core monk already does and in part has created this conversation.

Now for the first point that I'm going to do Last because it's going to take the most. But Kensai is actually also the closest example of Raizo when it comes to the monk class and mixing him with other monk subclasses doesn't actually help make a better fit.  It also only fits because of his dedication to his weapons in the same way the Kensai does that is above and beyond simple martial arts.  His Sickle and Blade which is the signature weapon that he carries on the cover art does not exist in the game currently but if you did create it the Whip is actually a poor comparison to it because the way they are used is very different.  Realistically if I had to give it stats I would base it more on the double bladed scimitar because it's the only thing that is even remotely close in function though some details would have to be changed. The rest of his weapons are just basic martial weapons reskinned that your already able to do by the way the monk and even the base game is written. There is no reason to even change how they function. Simply how they look and what they are called.  For the Record I think it's a really good idea for a weapon to be added into the game and I may consider homebrewing something like it at some point for my personal games.  I've always liked The Sickle and Blade weapon and the rope dart weapon because of their unique flavor and style that they possess.

But there are other details about Raizo than just being high level that would be required to represent him.  he actually has several stats that are above human limit but there is no good explanation for them because it was all simply through training for him. There is the fact that repeatedly in the movie he is injured fatally but survives it and even continues functioning that can't actually be represented by any subclass but Long Death and even that compares in comparison because the way he takes hits would drain you of all your ki long before it stops him if you want to do monk. Because his almost rage like quality and his ability to endure being killed and rebounding from it is only represented by maybe a Barbarian of certain possible subclasses or a couple of Races that he definitely doesn't fit with any closeness and can't be replicated by simply doing a custom lineage human because custom lineage is actually quite limiting in what it does despite people liking the shininess of it.  And the Shadow Powers he has at the end are just plain otherworldly. I might be able to find something with maybe something like the Ancestral Guardian Barbarian perhaps if I went back and analyzed the way that they manifested and the fine details of the kind of effects that they have. But it may be something that might actually be at least a minor version of some kind of actual magic over what most Monks do as far as magic is concerned and that's where my mind tends to lean for it.  Trying to put all of those things together isn't going to be anywhere as mechanically appropriate to him as a whole new class.  The Class that would cover all this probably would be OP by every meaning of the word in the end.  I say this because it's not just level that is fitting for what he does by the end of the movie. He's facing high level elite assassins with similar training to him in many on one combat with what should be overwhelming numbers for any single character and taking on even those that are masters which would mean higher level characters, Some of them in this same new class, and beat them.

Raizo really is one of those characters that looks really good on the action screen and is really fun to watch and Might fit in some Manga or Anime very well but they really do not translate to most other genre's or actual table top games with any efficiency.   The Avatar himself from the Last Air Bender is another one of these types of figures, That one actually is fully a monk but his actual abilities which break the rules of his own world.  These characters Do not translate at all into D&D, Specially D&D 5e.  They are just that above and beyond that they don't work with the change in storytelling style and medium in which the story is told.  So it's nice to try and imagine playing them but they are unrealistic expectations. That's part of what actually poisons a lot of people against the 4 elements Monk. They immediately hold it up against the impossible standard of the Avatar rather than any realistic portrayal of any normal person from that setting that are much less capable and then complain that it didn't meet their expectations and desires but it wasn't ever attainable to begin with.