The game is really cute I like it, think I want to note:
+ The movement is slow and jump is just you know, respectable, but the sword splash/dash is immediate it felt really jarring, I think it would benefit with a bit floating that dash up right away
+ For the boss fight I really like how you use the boss attack against it tho it took me bit before I realized I can hit the fireball back. But the problem is the lava don't do move, I just hug the corner and that it, I think it would be fun if there something to force you to move, maybe saw blade on the ground move back and forth?
But great job getting the game done :)