|The term 'Cut and Run' has a specific meaning|
That said, the 'pepper spray and folding knife' self defense solution can be problematic. Pepper spray is great - I wish every woman carried both a full power version in her purse and a small short-range version on her key ring. But pepper spray isn't always disabling, and if you miss your 'shot' or the guy has a high tolerance or your pepper spray isn't as powerful as they said it was - well, you've escalated the conflict and now you've got a physically violent confrontation on your hands.
But my concern with knives is greater. Don't get me wrong - I ALWAYS have a combat knife with me. But you need to understand what it's for, and how to use it. If you confront a bigger, stronger opponent and you pull a knife and wave it around and try to stab your way out, you're going to lose. Stabbing is like punching - if you aren't confident of your success throwing punches against a male adversary, you won't be successful fighting him with a knife.
So let's go back to basics. First, think about your knife. Is it big enough? Is it razor sharp? Can you get to it quickly, open it efficiently and discretely and grip it properly? These are things you can practice in your living room. Nobody needs to know. Get a good 4-5" combat folder, half serrated blade, and a sharpening kit. Don't use it as a screwdriver or a prybar. Keep it scary sharp, and keep it where you always know where it is.
Now. How to use it. Stabbing people is surprisingly hard. You need to expend a LOT of force to drive a knife deep into a human torso. But that's ok - we're not here to talk about lethal force. We're here to talk about crippling, disabling wounds that let you disengage and withdraw. You have three targets. The tendons behind the upper arm, the soft tissue inside the elbow and the major tendons in the back of the thighs. Anytime an adversary throws a punch or reaches to grab you, he exposes those muscles and tendons under the triceps on the back of the upper arm. If he's not wearing a leather jacket, reach up, cut hard across the outside of the arm, use the serrated inner part of the blade, and slash around the arm. Use a LOT of pressure - you want to do deep muscle and tendon damage. This damage will render the arm useless, and you will have a physical advantage you can use to end the fight and get home safe.
If you are out of position to reach the back of his arm, the soft meat inside the elbow - where they draw your blood at the doctors office - is vulnerable to a similar deep slash from above, rather than from below. You'll do less structural damage but you'll back him off by getting some spurting arterial bleeding that will scare him into disengaging quickly.
Finally, there's that hamstring tendon behind the thigh. There's also an Achilles tendon behind the ankle, but that's a secondary target. If you open your knife and hold it down by your side, you might be able to go to the ground, wrap yourself around his legs and drive the point of the knife into the meat of his thigh and saw it out. If you cut that tendon, he won't be able to walk - and you can leave, or call the police, or just go ahead and end him, if you want.
Look. None of these things are easy, and if you just throw a knife in your bag without thinking or practicing you're going to get badly hurt. Not everyone can use a knife in defense, and not everyone can do it even if they want to. But these are the realities of using a knife in self defense, and if you are carrying a knife out with you, you owe it to yourself to at least think about how you're going to use it effectively.