I met a diver that carried a short aluminum rod, only about 1/4" round and under 20" long with a landyard attached.
She explained that she used it to poke lobsters for picking, pointing out objects and sea life to other divers, and it functioned well to easily reach back and tap her tank to signel other divers. I guess you could just as well have SWAT that woman you were trying to get control of.