I believe in proportional force, responding to a thread with approximately equal force of my own. The court system does also, which is one big reason why I abide by the philosophy.
I don't carry weapons on my person; the whole reason why I have trained MA is so I wouldn't need one or be caught without one. Also, here again we have legal considerations-- if I crack some dudes orbital bone punching him with a knuckle duster, I'd be willing to be that if the issue of the fight comes to trial, the opposing attorney is going to ask why the hell I was carrying around a hunk of metal which serves no other function than to be slipped onto a clenched fist for purposes of beating the right to be out of someone.
I do have a two-handed extendable ASP baton riding in the drivers'-side door of my car. If I find myself motivated to use it, it will be because
1) I'm in a situation where even being behind the wheel of a car, I can't escape
2) I'm confronted by a threat that I do not think I can adequately deal with using only kicks and empty-handed techniques (being 6'3", 225 pounds, and trained means that this would be a pretty dire situation).
Beyond that, you can use all sorts of improvised weapons; anyone who can handle a short staff can go to work with a broom handle, pool cue, or similar item in a pinch. Bar stools work great against some pissed-off guy wielding a knife of busted beer bottle. That thing around your waist that holds your pants up (assuming you wear one...I almost always do) can be rapidly deployed as a ranged weapon (a metal belt buckle moving at high speed will gouge skin off your head) or, wrapped around both hands, a good way to block attacks and tie up the hand of an opponent that has a weapon in it to the point where he can be submitted.
Then there's yet another time-tested dirty trick for streetfighting: a roll of coins in your pocket. A roll of nickels is nothing but legal tender if a cop sees you with it; clenched inside your strong hand for punching, it's the best $2 you'll spend all year.