as I seen in combat the riot shield is dependent on
a) a team mate who is skilled to move an shoot, while staying back behind you,
b) not used in closed corridors unless you want to die to explosives aoe
c) players just running past you an gunning your guts out.....
I feel giving the riot shield the passive of being deployable with ONLY low-caliber side arm (preferably the one that does only 19 dam) but ONLY usable when the shield is down like half slanted exposing mid-chest an head, an cannot aim it can only hip fire.
I'm not expecting this to go anywhere it is just something that I thought of an I am aware that irl shield like this are nearly 40-50 pounds an by no means light, so it does make sense as to why it is not a mechanic at this time.