Low-level, trained MMA fighters would wreck a street brawling toughman 10/10 times. If they rush the MMA fighter with a broken bottle, they'd get slammed to the floor on their own velocity and the MMA fighter would twist around, take their back, grab and arm, get their legs around it pull. Good luck fighting with a broken arm.

We saw it play out recently. Remember Kimbo Slice? If you don't, he used to post videos of him beating the crap out of regular dudes in street fights for money. He became a legend. People were saying he was unstoppable. He went to the UFC based on that and lost just about every major match he was in. Why? Because he doesn't train for the various martial arts the way even the lowliest fighter does there. He's currently in boxing, now, and likely will be back fighting normal people in the street for 500 bucks again.

Seriously, you think guys who train 8 hours a day in Muay Thai and Jiu Jitsu aren't going to be good at beating you up? You think some street thug would rough up Junior Dos Santos or Anderson Silva? They would KILL the common man, likely in short order. A broken glass would just make them more careful about it (and piss them off even more).

This isn't even to say if Silva grabbed a glass, too. Then what?

That is the problem with painting the martial arts with such a broad brush. Many styles have techniques specifically designed to deal with knife/gun/weapon attacks, and some styles are designed mostly around dealing with such things.

A broken bottle is probably not as dangerous as you may think. A knife, you are probably going to get cut but your attacker will fair far worse. A gun becomes less useful the closer an attacker is, during something like a mugging, they are typically very close.

But, even when learning how to deal with an attacker with a knife or gun, any decent instructor will tell you the best response is just to give them what they want and get out of there. It is the same as when engaging in just a fist fight, it is more a matter of 'is this worth it' or 'do I have a choice here' rather than 'can I take this guy'.

I guess I understand what you are trying to say, but you can't seriously think you, with a knife in hand, are going to kick an unarmed Bruce Lee's ass?

(using Bruce Lee because he is internationally famous, but assume I mean any world-renowned, elite trained multi-dimensional fighter)

The person still needs to be trained how to use a knife in combat. Have you ever stabbed anybody? (I haven't) but it seems obvious that it would be a lot harder than you'd think. (what is the proper grip? how do you thrust, how not to break your wrist, obviously can't go lunging blindly because if you miss your momentum carries you to a defenseless position... lot's of things going on here)

I guess it depends on what form of martial arts you are talking about. Some only focus on "dirty fighting". The whole purpose is to maim the other person so that they have no choice but to quit fighting.