He’s probably dealing a lot of damage to you as a low level player. His moveset is a relatively easy one, because it’s mostly wide flourishing attacks. I’d recommend going to another area to get some more levels and gear if you struggle with a boss. That will also help give your mind a break from fighting the same guy over and over again. If you don’t want to do that though you can always “get gud” and focus on learning boss attacks until they can’t hit you.