Great job! I played to the finish and really enjoyed it. It started with platformer/Hollow Knight vibes, but the main event and highlight was the head-to-head scene. This was definitely among my favorite combat scenes or boss battles on an Itch game -- really good work! It felt fast-paced and exciting. I had to try different strategies and it took many repeat plays but I finally beat it, which felt rewarding. (I never hit the "compromise" button, not sure if that changed the combat or similar.) Great battle animations, as well. Keying was perfect for me (Celeste style).
As far as feedback for further development: the moves felt a little slow or delayed at first, but I adjusted to it and it felt fair. Separately, I tried out the block move in both the platforming and battle but ultimately didn't use it at all, as it seemed like it made me vulnerable and I had trouble fluidly going from block to strike, and lost gray bar in the process.
Nice work!