wait did he HAND him the weapons just then? because if not, wait for him to go to wherever he has all his weapons and goods. that way, we can take him out, and then loot the forget out of his crib and get BANK.
or we could have one of our lackeys go up and pretend to buy guns, then draw him his attention completely (maybe discuss one of his CURRENT guns he has or something) and then someone else can come up and either shoot him in the leg or knock him out idk.