Most states have laws saying that you can use deadly force if you reasonably fear that you are in immediate danger. You don't need to see a weapon nor does your attacker have to be holding one to cause you to fear for your life. Ten guys beating on you? I'd fear that. I'm a fat old man in poor health. You think I'm going to fistfight some 19 year old stud? No way, Jose. I walk away from any argument and if he won't let me walk then I shoot his ass dead because he'd seriously injure or kill me in a fight. In Texas a couple years ago one guy was beating on another man in a case of road rage and the driver being attacked shot the attacker to death. He feared for his safety. Ruled justifiable.