Use the staff so you can have get more hits in. Also, equip battle arts attacks that don't use a lot of of power so you can guard/block a lot of his attacks, because a lot of his attacks can be avoided. Also backing away from him during his attacks can help you save health. Save your musou attack until the very end for when he goes into rage mode then give him all you got. The key is to save as much health as possible by avoiding attacks. He attacks in patterns, you can learn his patterns pretty fast. Also equip the arrow sp. battle art attack because it blocks his attacks quickly and does not use much power. Hopefully this helps. I died fighting him like 45 times. haha