Very fun work! Love the art, animations, and the level of polish in general. I did find a bug where tapping X and then tapping X a second time instead of any directional keys cancels the magic stance but stops me from moving afterwards. Thankfully, casting any magic allows me to move again. The boss at the end was confusing at first, but I managed to figure out the solution to use the guard eventually. Armchair gamedev time follows:
The issue is that since you can chain stun every enemy to death, it is never strictly necessary to use the guard (or the blink move for that matter). Perhaps the melee enemies could hyper-armor through the player's attacks, but guarding their attack stunned them. Something to that effect could teach the player an application of their guard that they can use during the boss.
While I'm here wishing for things you could do to expand on this framework: I really found myself wishing there were ways to cancel your attack recoveries into the magic stance. I think you could design a really really fun combat system around doing that.
Anyways, what you've made here is already really awesome! By the end of my time playing, I was really getting into throwing Sherry Bombs to soften up groups of enemies to take down in melee. It was super satisfying! I think what you've built here is very ripe for expansion into something else. I am excited to see what you do in the future!