Ahim's the ship's best marksman. Where Marvelous is well-balanced with both sword and gun, Joe's the two-blade swordmaster, Luka's got her Kratos trick, and Don's got his derp-fu, Ahim's at her best when she's just shooting the fuck out of things.
Actually, given what we saw in the Accel movie, I have to wonder if Don and Jinno ever trained together.