I think you did a great job with the art, even with the minimalistic pixel art all the post-processing and HDR lighting makes the entire thing really pop. The tutorial at the beginning is great at introducing the concepts too (and kudos for not making the player go through it every time they die lol)
I think my main gripe about the game is that the transition between guard and attack feels really wonky. Like, I have the impression there's a window after attacking where you can't guard? Maybe it's just me
The main thing I think could help is making the guard stance more obvious. Right now, it's a stance that's barely different from the default one, and the reflect on the blade takes too long to come out, so it's hard to see in the middle of a fight. Maybe changing the character's light colors from purple to say, blue? That way we can tell right away when we're safe, and it's easier to know when we can parry and when we can't
Also, having the boss' fireballs be homing (they feel like they're homing?) is really harsh when you can't parry in the air lol
I focused a lot on the negative for this one, but even so I actually like this game! I kept retrying after dying at least 20~30 times, so there's definitely something nice going on :) One last thing, adding a pause menu is a small QoL that can go a long way, and doesn't take that much time. Overall, great job :)