If you want a self-defense weapon that you always carry with you, use the one on the bottom end of your leg.
And I'm not talking about kicking with your toe unless you're into ballet.
You know how you stomp on a tree branch to get it to fit in the campfire? Use it on your enemy's knee, aiming at the front or side of his knee, and do your best to fold his knee in the wrong direction.
I can tell you that it will put someone down and it hurts like h***. Properly administered, it will rip the tendons and the former-terrorist-now-victim won't be going anywhere in a hurry, if he can move at all.
He may be able to protect his eyes and his groin, but he can't do diddly about his knees.
Mean, nasty Sue <img src="/images/graemlins/frown.gif" alt="" />