"Drunk guy picks fight...shoving and punching occurs on both sides. Knife or gun gets pulled."
Bardo, this sort of "what do you do" exercise has no right or wrong answer. I'm not a superhero, crime fighter or LEO. If he's my friend, then I'm absolutely gonna' sheepdog his stupid ass OUT of the situation by sudden and ideally less-than-conventional means. You can't reason with drunks, ever, but I have unfortunately enough experience to know that surprise & confusion provides much better leverage. There are a thousand immediate, situational details to observe before I decide what that action is gonna' be. I'm creating and evaluating response scenarios with the raw urgency of a tail-spinning pilot! How drunk are the other guys? How near is the exit? Where's concealment? Where's cover? Where's the bouncer? Is everyone freaking or is this an every-night event? etc., etc., etc. You can't PLAN a response, you're playing defense, so by definition you can ONLY respond.