Not to stray too far from the original topic, but what would you recommend when carrying a firearm is not an option? Mace/pepper spray?
No problem at all. I'm from Maryland where we can't get pistol permits (we're a "may issue, but almost never do" state), so non-firearm SD weapons get a lot of discussion and testing in my circle of friends. Now please pardon if I get a bit longwinded.
Knives have their place, but are limited. A knife does only two things in self-defense: Scare, and kill. I and hundreds of others have scared a potential attacker away by brandishing a knife. But it becomes a problem if the attacker is drunk or just plain stupid and calls your bluff. Then you have two choices: switch to another weapon, or kill them. Knives cannot be reliable used in a non-lethal manner, and I have read several court cases were an unarmed criminal attacked someone who was carrying a knife, the knife was used in defense and unintentionally killed the attacker, and defender ended up going to jail for manslaughter (because it was considered unjustifiable deadly force against a non-deadly threat). Only two cases I read where a knife was used and the defender was acquitted, and both involved the defender being knocked prone with the attacker on top of them.
Pepper spray is not to be underestimated. I have found that most of the reluctance to carry it is based on unreasonable or unfounded stereotypes. Often I have noticed that males tend not carry it (favoring a knife instead) because they think it's a "girls weapon." That's dumb, why should any weapon have a gender tag? It does the same thing to anybody, and obviously cops carry it and put it to use all the time. Another is the alleged "effectiveness," the argument that some people may not respond to it or can fight through it. Well, some people don't respond to bullets in the center mass either. No weapon is a magic wand that works 100% of the time. And pepper spray is actually more successful when used by a civilian than a cop, because the civilian isn't concerned about subduing and cuffing. You just have to run the other way and your pursuer is now blind and dyspneal. Fat chance catching you.
Last item is blunt-force weapons. While a lot of purpose-made weapons might be restricted, a surprising number of non-weapon objects perform the task just as well. Anything that is a 16-36" cylinder of reasonable density and durability is a perfectly good billy club. Maglites, pieces of wood, walking sticks. When I was in college my friend used to carry a 24" piece of thick heavy duty fiberoptic cable sticking out of his backpack. He was a communication engineer so it was easily explained as one of several "spare parts for his class project." Get creative, I'm sure there's something you could explain away easily that would do the job.
