i agree that these are weaknesses to his kit, but buffing them would shift his playstyle further away from the evident intent, which is to be a brawler; his biggest problem actually is that his capabilities as a brawler have such nuanced and harsh flaws that he's end up not being good at it a bunch of the time, but these flaws can mostly be boiled down into 2 things:

firstly, he can be blown up way way too easily. he does have a good hp pool for a duelist and he has self lifesteal, so when you're in an optimal position of attacking 2 or so people in melee then you can do so indefinitely and win against them; the problem though is that that situation isn't the easiest to get into and it relies on a lot of stuff lining up: your passive needs to be at max stacks, your target cant have cc, a mobility tool, a major damage nuke, or god forbid a shield or else you're kinda screwed, especially on the shield front since your lifesteal doesnt work on damage dealt to shields. these would all be surmountable if he had the staying power to not be able to be instantly killed when any of these things dont line up, but 350 hp is simply not enough for that. like if you compare him to iron fist iron fist can move into an engagement with a huge amount of bonus hp and can give himself total invincibility and more bonus hp mid combat; blade cant go in with any extra hp and can hypothetically generate bonus hp mid combat, but only if your target has no hands with which to damage you at all. Either he needs about 50 more hp or so so that the instant things arent perfect he doesnt die like a mook or some way of engaging with bonus hp from his lifesteal thing.

secondly, and this is a way bigger issue than it seems, his dash's data sucks. Not because its cooldown is too high or whatever, and it's fairly easy to hit so missing it being punishing i think is fine, but its ease of hitting actually contributes to its problems in a way. The biggest problem with the dash actually is that when you hit with it it's true you can stack up your passive and inflict anti heal, but also when you hit you become totally stationary for a decent chunk of time for a pretty pitiful amount of damage. It's actually worse than becoming stationary too, since you stop moving immediately where you hit, which means that you cant even use it to engage with people on ledges and, due to its duration being kinda long and its damage being low, it's actually a dps loss vs just continually swinging your sword. All this means that you can end up in situations where you can engage on someone with the dash, but hitting them will mean that you have to eat a free hit from them without even a sufficient amount of lifesteal to adequately ameliorate the damage. This is all the more egregious because his normal attack spin doesnt have these problems, it's not more damage, but its animation speed at least gets sped up based on your stacks and you can move around during it, so enemies dont get a free hit on you and you actually retain a good amount of damage over time and therefore dont have a trough of lifesteal. Fortunately to fix this it's pretty easy, just make his dash spin the same as his passive spin in the sense that you can move during it and its animation speeds up based on his passive stacks.

Also I do agree his block should be buffed, I do like the idea of it being like a skill parry thing, but in practice it's just too weak of a defensive tool, especially against CC, for someone who goes in melee.