I like the weapon and the animation, it is great.
The first friction i found is when the character touches the circle obstacle, sometime the character will stuck right there or shake. The second friction is after i click "Change Env" button, i press the space button to attack but it also changes the environment every time i press the button.
One thing you can improve is the text, it is hard to see because the color is same as the color of obstacle. I recommend you add the outline or change the color to be more visual. And the "change Env" covers the text that show how long the posion last (hope it make sense).
For the itch page, add some arts and some detail of the description (like after i kill the monster what keys can i click to stay a human or turn into the beast?).