A "chemist" healer idea might work pretty well with it. They don't even necessarily need to shoot potions, they could still throw em, with the weapon just being a... weapon.

Alternatively if we do want to shoot potions, the healer could use something more akin to a grenade launcher instead. Or if we do use the rifle, who says it has to shoot anything physical - it could be healing aether. Etc.

There's a lot of possibilities, really.