Just lock the heavy weapons, ghouls can't use them anyway.
And running won't be possible anyway, so there will be actually even less animation used.
Also, explaining that it would be impossible and dangerous to use heavy weapons with robes (entangle and fire hazard), thus making robes available for normal players as well. I mean, SmallGuns and Running animations are there.
Ghouls are slow. There are two different ghouls skin, the green one (Harold's skin) and the Scavenger's one (Lenny skin). Green can use rifles (Small gun skill only) and Scavengers can use pistols. To give a particularity to the ghouls, it's better to make them able to use the rifles instead of the pistols. So green skin seems the best choice. Also, because they are slow, using pistols only would be a real suicide.
Inconvenients :
They can use only rifles (small gun rifles animation).
They are very slow. I mean they are REALLY slow a lot slower than a walking human.
What can we give them as qualities ? Ghouls can use rifles and are slow. They would be perfect as snipers ! They also could be smart. They would be wonderful crafters, also, or doctors.
So here is what I suggest for them :
SPECIAL : Maximum strenght : 5 ; Perception bonus : +9 (So they all would have 10) ; Maximum Endurance : 5 ; Maximum Charisma : 1 ; Intelligence bonus : +3, Agility : -3 (Max. 7) ; Luck : Same as normal.
Jinxed trait.
Radiation resistance : +50
Damage resistance : -10
Various % bonuses to skills Small Guns, Doctor, First Aid, Repair, Science.
P.S. Robes makes the game a little more honest