1. make sure the knife isn't pointed at your body. If it is, direct the initial force sideways or down.2. Make sure to keep your arms in front of your chest and stomach to avoid fatal stabbings. Slouch the shoulders. 3. Try and kick the knife out of his hand with a roundhouse or a low axe kick. This is useful because the legs provide range to force the knife out of his hand by kicking without moving your body close to the attacker. Also, wearing shoes will provide defense while kicking the knife so it won't hurt much. 4. Push the attacker away or move back. A push- kick is good for these situations or a back kick. 5. Hit the vital points. The kick or knee the testicles or the thigh to make him buckle. 6. Cup your hands and slam them against the attackers ears with both hands. This will give the attackers a ringing sensation in his head which will make him temporarily off balance and will cause him to lose senses. 7. Headbutt or punch his nose to create irritation. The nose is one of the most irritating part of the body to be hit by. This will cause you be get close so don't resort to this option unless you've been stabbed already. 8. Hook punch the cheek or chin to knock him or daze him. (i would kick his head but many people aren't that flexible and don't have good technique.) This is the best thing to do before he hurts you. But make sure the punch is very strong. (one shot kill) 9. straight punch the solar plexus. This will cause him to drop his knife or lower it. 10. Relax. 11. Run away. hope i helped.
4th dan ITF taekwondo black belt Judo practitioner 5 years. DMZ south korean military warrant officer
It's a good idea to get a plastic knife and practice with a friend, disarming him.