If your goal here is to curb grenades' power without directly nerfing their damage then I dont think Grenadier is the place to hit, even without it you can pretty consistently decide fights in just one damage grenade by aggroing -> fleeing to let enemies dogpile after you in a tighter group. I'd take the route of restricting higher-quality grenades to Throwing-centric builds with a skill requirement; this could be strictly gating their use to a certain skill threshold, or treating it like Trap disarming and introducing a 'critical failure' for grenades where they fly behind you, wildly deviate much more often, or just blow up in your face when your skill is too low.
