Legendary ryoma

brazen Attack/speed would probably serve you best.

Depents on the build.
But usually you'll want to combo brazen skills with other low hp skills. So that would mean going for:
Raijinto, Glimmer, Brazen atk/spd, vantage, brazen atk/res (seal).
Normally Raijinto isn't the best for him, but it could work for oneshotting mages like this

I didn't mention desperation because you're better off giving him a firesweep sword together with glimmer, life&death, bushido and flashing blade. He kills a LOT of enemies with that combo.

Lastly you can go more budget with Kestral stance, close def and either slaying edge or safeguard. Refined for def, since you'll have more than enough speed.