The only good part about my wife being deployed to Iraq is that I no longer have to suffer through "What Not To Wear" in the afternoons. But since I do miss her, I thought I would do my own version of it with "What Not To Carry"--big mistakes a lot of people make in an honest attempt to be safe.
1. A Knife
I'm not against carrying a knife to use as a tool. I carry a big locking folder from Columbia River Knife and Tool (CRKT--my favorite knife maker). A knife can be a life saver from a utilitarian standpoint. Say you get in a car accident. The car is on fire and your seatbelt is jammed and the 19 airbags inside haven't deflated due to a malfunction of some kind. The doors are stuck shut also. Well, with a big folding knife like my Desert Cruiser (or any other big folder with lots of metal in it-- Desert Cruiser pictured above), you can pop the airbags, cut yourself free, then fold it up and use it to shatter a window and escape. A knife can be very handy indeed. But unless you are Ninja, pulling a knife in self defense will only end with you stuck to your own blade.
Most people that I have talked out of carrying a knife were women...who wanted to carry a knife to "scare an attacker". If you pull a deadly weapon, you better intend to use it--and stabbing someone to death is hard (so I've read in my criminal justice classes). Stabbing into bone is like stabbing into concrete. Most slashers are caught because the knife pops back across their own hand as the blade bounces off a rib, leaving a tell-tale sign on their hand. Conceivably, a novice knife fighter could deal as much damage to his own hand as he does to his opponent. A knife requires a great deal of skill, training, and will to use it. Even then, slashing wounds can take hours or days to cause incapacitation. Stabbing wounds can be substantially more effective, but a masterful knowledge of both human anatomy and knife-fighting skills is required for someone to be able to count on landing such a strike. That's why you should not carry a knife for defense (unless you are a ninja. In that case, go for it.).
2. A TASER
Fancy TASERs like the one above fire two prongs into your would-be assailant and, for three to five seconds, pass huge amounts of pretty harmless electricity through his body. As soon as the cycle is complete, you can pull the trigger again and send him on another five second ride through Painville. However, once the prongs come out, the batteries die, or a wire breaks, he's good as new in short order. You may or may not have time to escape or time for the police to show. Once the cartridge is spent, you must reload or choose to use it as a cattle prod. The problem with cattle prod mode is that the pain only occurs in the muscle(s) between the two terminals. It causes pain while not causing any permanent incapacitation.
The TASER is a great tool for cops who need to take belligerent suspects into custody without harming them. Their only option just a few years ago was pepper spray (everyone loses...trust me) or going hand-to-hand, which leaves plenty of opportunity for both parties to sustain permanent damage. The cool bit about the TASER is that nobody is resistant to it like you can find with pepper spray. Civilians may or may not find the TASER useful. It might give you a chance to escape, but if you're confronted by more than one bad guy, then you're pretty hosed. If you use it in cattle prod mode, you have to get up to contact distance with your attacker. I'm not sure I want to do that.
3. Itsy-bitsy Cans of Pepper Spray/Mace
Sorry, wrong sort of mace. Cool though.
Okay, here's the stuff. I actually like pepper spray or mace (two different things, but the differences are so technical that they even bore me). I've seen this stuff work wonders. But you have to have a decent sized can of the stuff to make a difference. I keep seeing itsy-bitsy bottles of the stuff in supermarket checkout lines and on gun store shelves dedicated to stuff just for the ladies (I guess pepper spray isn't very manly?). First, some people are not effected much or at all by this stuff--which is bad if you're attacked by one of these people. Second, if they keep sustaining the attack after they've been sprayed (he's on meth or something) then you get to share in the burning sensation because it will rub off on you! How fun! Third, tiny bottles don't have enough juice in them to hit two or more targets with enough product to cause sufficient pain. Additionally, I've seen girls have negligent discharges with these things in public places, which is more than embarrassing.
4. A Gun You Don't Intend to Use
Back to the idea of "scaring" an attacker away. A gun might do that. But it might not, and if you don't intend to pull the trigger, you'll probably get shot with your own piece. If you aren't willing to fire it at an attacker, don't carry it. Period.