Determine whether you need your folding knife for self-defense. If you pull out your weapon first you may be the one arrested for assault with a deadly weapon. The same could happen if you have an opportunity to run away but do not take it. Only use a folding knife for self-defense if you have no other option. If you are trapped and an attacker pulls out a weapon first, you are justified in defending yourself.
Unfold your knife. It takes a few seconds to pull out a folding knife and open it. Do this before you are being attacked, or you may not get a chance.
Hold your folding knife with a Filipino grip. This is the way to hold a knife preferred by fighters who know what they are doing. Grip the handle of the folding knife firmly with the last three fingers of your dominant hand. Wrap your index finger loosely around the handle and point your thumb toward the blade. This grip keeps the base of the knife firmly in your palm while allowing you great freedom of motion.
Stand in a knife-fighting ready stance. This is somewhat different than a ready stance for unarmed combat. Your knife hand should be forward but tight to the body so it can't be knocked away from you. Your other arm should be perpendicular to the ground, guarding your body with the hand by your chin. The foot under the knife should be forward while your other foot is one step back. Your feet should be shoulder width apart.
Warn the attacker in a loud voice that you are armed and prepared to defend yourself if necessary. This is an essential legal step before you can use potentially lethal force. Urge the attacker to walk away so that no one gets hurt. Try to attract the attention of witnesses who can confirm that you tried to avoid the fight.
Slide in a 45-degree angle toward the attacker. Do this toward your knife-hand side. This makes you harder to hit and exposes your attacker to your counterattack.
Block with your free hand. Grab the attacker's arm on the side where you are sliding. It does not matter whether the attacker has his weapon in this hand or the other. If the weapon is in this hand you are shielding yourself from it. If it is on the other side you are moving away from it.
Strike the attacker's torso beneath the arm you are blocking. This can be a slash or a jab. Be aware that a jab will cause more damage but must be done below the ribs or it will bounce off. Since the object is to stun the attacker so you can get away and not kill him, a slash is preferable.
Run away. The moment you can get away from a knife fight you should try to escape.