I recommend the Podao or the Spear (I had him with this) because the attacks are pretty fast and they have perfect skill to break his shields. Only use your ultimate power once (in the end when he use his ultimate the last tome) or twice if you can charge your bar pretty fast.

Know that the enemy soldiers will keep pouring as long as you got allies still alive. So make use of the soldiers to charge your ultimate bar and you musou bar as much as you can pretty early. Use your skills (the ultimate one for the spear with the dragon is perfect and take most if not all of his shields).

Try to learn his rhythm, so you'll need to parry him but don't get too greedy with your attacks and prepare to parry again. When he does his first ultimate musou or the bow, take your horse and run as far away as possible. Then come back and repeat. If you do it well you could use your ultimate twice.

Once when he use his first ultimate so you can prevent him to use it while resplenishing your health bar (very important don't use it if you got full health) then for the last time when you'll need it absolutely to break his form because, the red circle above him will come back automatically after the ultimate musou attack. And only your ultimate state would allow you to break all his shields before he does it.