Now true knificionados will say, "Useless, lousy steel, won't hold an edge, will rust, ugly, ergonomically challenged," etc. etc.
Two things to consider when picking a knife for self-defense.
1. Will the knife hold up to the use for which it is intended--even if it's to be used only once?
2. Is there something in the knife design that will reliably keep hands/fingers from sliding down on the blade. Many a knife murder has been solved by DNA matching blood left at the scene when the attacker cut himself with his own knife. This kind of injury can be really nasty--it's definitely something you want to avoid.
A few other things to consider:
1. Knives disable two ways: Physically damaging a limb (cutting through a tendon/ligament or muscle) to the point that it won't operate properly, or by severe blood loss. The former is more difficult than it might seem. The latter can take a significant amount of time during which things could be very unpleasant for the defender. Even really wimpy firearm calibers provide at least SOME possibility of an instant stop via a CNS hit. Not saying it's likely, but it's a possibility--which is something to consider.
2. Knives are contact weapons. If you can injure an attacker while they are still out of arms reach, that's tremendously preferable to having to go hands on. Also, if the other person has a gun, they may be able to incapacitate you at a distance before a contact weapon can be brought to bear. Contact weapons are great
when nothing else is available.
3. I don't have a link to the study by Gary Kleck any more, but I'll quote it anyway from one of my old posts: Resisting violent crime with a knife is one of the top 3 strategies that are most likely to result in injury. The only two strategies in the study that were worse than resisting with a knife were resisting with your bare hands, or trying to frighten the attacker off/call for help. According to the study, resisting with a firearm was the best strategy for remaining uninjured.
Besides, as the saying goes, knives are useful for fighting your way to a handgun, and handguns are useful for fighting your way to a rifle, which is useful for fighting your way to a shotgun.
While I can't recall ever having heard of a non-LEO self-defense encounter where a person actually did use handgun to fight their way to a long gun, it does make sense that, in general, a long gun is going to be more effective than a handgun.
However, there are really good reasons why a person might be unable to carry a long gun, or have one immediately available. Much harder to come up with a reason why it's not possible to carry a handgun or to have one immediately available but still be able to have a 10" kitchen knife handy.
All that to say that I wouldn't recommend making knives a first line of defense unless there's some reason that firearms can't fill that position. As a backup or last ditch self-defense weapon to be used after a firearm runs dry or in situations where firearms aren't available? Sure.
And, for whatever it's worth, I do own some defensive knives, have some edged weapon training, and certainly am not trying to argue that they can't be used effectively for self-defense. Just that it's important to understand their limitations.
