I wish I could remember the specific article by Richard Ryan in Black Belt Magazine that discussed this, but here goes anyway...
Are any of you familiar with the basic forearm shield defense espoused by JKD instructor Richard Ryan?
About 6 months ago I started incporating the shield defense into my inconsistent practice. After years of conditioning different defensive strategies, I have found that the shield defense has all but taken over my defensive strategy in under 6 months. It just feels so natural and effective. Gone are my days of Pak Sao and Tan Sao =) Now when someone throws a playful attack my way I find myself moving into a shield defense before I even have time to think about it, and rarely does anything penetrate.
As I practice it, the forearm shield basically consists of both arms brought in front of the chest at about a 45 degree angle. There are four primary applications of this as follows. Note that this defense still adheres to the principles of sensitivity, economy of motion and redirection...you should not meet force with force.
1. For a circling attack like a hook punch or haymaker, your forearms thrust into the bicep or forearm of the attacking hand. This operates like a stop hit but keeps you covered if you screw up.
2. For straight punches that need to be parried you can redirect with your fore arms or simply use the appropriate arm to throw a sweeping elbow to intercept and redirect the attacking arm.
3. You can drop one of your forearms to cover your ribs / kidneys much like a boxer does.
4. When it really hits the fan you can drop your body, cover your face and torso and move in and through their defenses.
Not sure how safe this would be against weapon (especially knife) attacks, but then I believe in simultaneous attack and defense, so it isn't like I would just sit back and try to defend over and over again