First of all, congrats on making the game. I love the idea of playing as a sword, music is great too as are visuals.
Exploration - a lot of the areas didn't have chests and when I found a chest, nothing was in it, where you kinda want to reward players for exploration so it made me not just explore at this point
Difficulty - The game was slightly too easy as I got to a point I could just leap over enemies and get by without much effort.
Enemey variety - Different enemies would have solved this, I think you could have done some cool things with different kind of attacks too, like you do for the jump, which could bring into play new enemies.
Controls - I wasn't huge on shift being attack, as oppose to something like space bar and having jump as W.
Game juice - This could have been cool, like camera shake when attacking more, maybe a strike would knock them back or split them into more enemies making it more difficult (different enemy type)
Still a really cool idea, and some things that could be added if you wish to take this further. Well done on completing a game jam though. :)