West The Riki Riki no Mi should have a bonus damage modifier that helps Brawler class damage. It could also boost techniques like Shigan, Rokuogan, and maybe even some of the fishman karate moves. It would be fun to have a Devil Fruit with background passives like that.
Drqonic It'll just make you deal high damage through attacks that directly use strength, so any non-projectile physical attack. No class specific changes