There are a lot of questions that come in regarding knives for self-defense. Obviously, a gun is a better tool for self-defense overall, but different circumstances, perhaps restrictive laws, may make this more difficult, or impossible for some people.
The next step down is a blade. Thank God I live in Texas where, if I choose to do so, I can strap a sword on my hip before heading out. Okay, I could legally do that, but some nosey do-gooder busybody would call the Police and I would have to answer a lot of questions, and that would lessen the fun and raise my blood pressure. So, scratch that idea.
Most of the questions about knives as self-defense are about what type of steel is best for self-defense. People hear that stainless steel is brittle, that carbon steel rusts easily, and so on. I get some questions that I don’t even know how to decipher, such as molecular structures of different steel types.
I want to cut through (hahaha, that’s very punny) some of the non-essential stuff. If we are speaking strictly about self-defense, a lot of what you hear does not matter.
Stainless steel is brittle after you reach a certain blade length. That length, depending on who you ask, is about one foot. In most jurisdictions where you are not allowed to carry a gun, they also restrict your ability to defend your life with a blade. Until the most recent changes to Texas law, we were restricted to a blade length of four and a half inches. So the often cited brittleness of stainless is irrelevant.
Carbon steel will rust. My favorite kitchen knife rusts between the time the dishwasher finishes its cycle and I get home from work to empty it. Wipe the blade with a paper towel and apply some cooking oil and it is good as new. This really is nothing more than a matter of taking care of the knife. If you opt for carbon steel, don’t put your self-defense knife in the dishwasher. In some climates, such as coastal areas, carbon steel is a poor choice unless you are meticulous in your blade maintenance. Saltwater air is rough on carbon steel.
What is more important than blade material is training. If you are going to use a blade as your self-defense tool, you need to train to use a blade. You need to know the laws regarding self-defense where you live, and you need to train. You can make yourself crazy looking at knife reviews online. I have a Bowie knife. There is a review of my exact knife on Youtube, and the guy destroys the blade by trying to chop down a tree with it. My blade is completely undamaged after seven years. You know why? Because I don’t use it to chop down freaking trees.
Short form of the above, what matters about a blade for self-defense is that it is sharp and you know how to use it legally. Unless you are in a war zone, even thoughts about edge retention are unimportant side-issues. If you are talking about long-term survival in the brush, then we need to put on a pot of coffee and tire the moon with our talking.