i recommend strongly against using a knife as a self-defense tool.
1. to use a knife effectively, you have to have the intent of killing. not everybody can do that.
True. A knife constitutes deadly force. If you haven't made The Decision (as the firearms types call it) you don't have any business using that tool. If you're serious about self defense against actual violent crime you really need to carefully consider The Decision and plan accordingly
2. any sort of knife you can carry is very short range. better to stay further away.
If someone is really trying to hurt you there are two possibilities. One is that they will stay far away. If they do and you are bigger than them, congratulations. You aren't in a fight. If they are bigger than you (more likely) and you stay out at range trying to play knuckle tag you will get beaten to death.
It's more likely that they'll get up close and personal. Everyone who tried to hurt me did unless they had a weapon that increased their range even more. And then you
really want to be in close. To a great extent effective self defense begins when you stop saying "No. No. No. Stay away!" and switch to "Mother-lover!" (or something kind of like that) and show willing to tear their head off and beat them to death with it.
3. knife wounds look nasty in court later. the difference between self defense and aggravated assault sometimes depends on the jury.
4. cops often hate knives. they will be less likely to give you the benefit of the doubt if they see that you cut somebody.
You need to understand the law. You need to know what you are doing and why you are doing it. You need to be able to articulate it in court and defend it. But if the choice is dying now or possible legal trouble down the line you need to make a decision about which is more important. Personally, I'd rather be alive to deal with those problems later. If it's not a choice between that and dying or similar - being raped, having my house burned down around me, getting mugged, forcibly sodomized or forced into the trunk of a car - a knife is not the right tool. If it is, then even a two-inch blade is a great comfort.
5. three words: aitch eye vee. getting bled on by drug users is not a good idea. (see also hepatitis)
Getting HIV from having someone's dangly bits shoved into your bodily orifices is even worse. Getting shot, beaten to death or stabbed isn't very much fun either. Even getting into a fistfight can spread body fluids. If the situation has escalated to the point of deadly force you need to discount the possibility of blood-borne diseases a bit so that you can stay alive to deal with them. And if your measures mean that he is doing the bleeding and you aren't your chances of getting infected go down dramatically.
ibelieve just as strongly in knife training. knowing how a knife is used is an important part of defending yourself against a knife. also, ten minutes of solid knife training will put the right amount of fear into you so you avoid knife people at all costs.
but don't carry a knife for self defense. carry an asp, a tactical flashlight, even a gun. canes are nice. or better yet, rely on your awareness and good sense.
Yes, knives are effective. That's why people use them. "Ten minutes of solid knife training" is like saying "I've had ten solid minutes of boxing. I know I don't want to get punched". It doesn't amtter what you want. It's keeping them from getting what they want. If knives are that scary and effective in the bad guy's hands they are that scary and effective in yours. And they are likely to be legal in places where a gun or a collapsible baton will be a felony.
Like all tools knives are just tools. But in their proper place they are incredibly effective. And when they are the right tool for the job they will save your life.