Damaging them when sheathing the weapon feels very anime, I like that very much!
That in itself is a rewind mechanic, which is smart. Though it would be great if the targeting was more accurate to the point of the click since we're using mouse buttons. I also agree with others for an indicator in which the enemy has been slashed. Plus, an anticipation animation from enemies would help warn us players for an incoming attack.
But anyways, cool stuff/concept, reminds me a lot of Nioh 😄