You're welcome! The most basic form of hit feedback is just a bit of hitstun and flashing,
so when an enemy gets it, it temporarily slows down or gets stopped completely, and maybe even visually changes (with a sprite or by modulating the color to something brighter), until they get back up to speed. That also makes the attacks feel weightier because the enemies are physically affected by what you do to them, instead of having their internal health value decreased (which the player doesn't see)
Oh and btw, the bloodseeker was available from the start haha, I just navigated to the skin tab and could change that way, but it honestly felt way better that way (at least for a gamejam, where players are less likely to spend much time with your game!)