That said by the end I was really starting to get into it. I understand parrying, although I think it's a clunky system because it depends on which way you're facing the enemy and the camera is awful in this game.
Let me say that I didn't have many issues during the span if the game or any of the other bosses.
So I've just spent an hour on the final boss. When switched to windowed mode it ran at 60FPS and I had zero issues getting through that section. EDIT: I beat it - turns out the game was running at a subpar framerate in fullscreen causing me to always mess up the zandatsu slashing thing.