Cool concept! Staying alive in that last area was pretty fun :)
It felt like actually lining up the sword launch and the enemies was kind of pointless (I feel like that would be the first thing people try since it's not immediately clear that the rotating sword also damaged the enemies). The optimal strategy seemed like it was to group up all the enemies into a big clump, and then fire the sword ahead of them so that when it starts rotating afterwards it hits them all multiple times. I also grouped them up at the start of each level before I activated the sword because it damaged all of them when it got activated.
There were some issues with the sword not launching properly because it was slightly inside of the outer wall after rotating to face the player.