To use the hand as a weapon requires it to be strong in all actions. Not only must the action of gripping be strong the motion of opening the fingers from the grip must also be strong, as in releasing the hand from a grip.
Most people strength train their arms, legs, and abdomen but neglect their hands. Mas Oyama, one of the most powerful martial arts of this time (he fought and killed bulls barehanded), describes hand and finger exercises in his book Essential Karate. One exercise consists of placing the palms and fingers of both hands together in a prayer-like position with the fingers pointed upward in front of the chest. The hands and fingers are then pushed together in an isometric manner. While maintaining the pressure, the hand are raised above the head and then lowered to the level of the solar plexus. The same up and down motion is used with the finger are pointed away from the body and then with the fingers pointed downward. These motions strengthen the wrists, arms, and chest, while also building flexibility in the wrists.
To strengthen the fingers and wrist, perform pushups on palms with fingers pointed inward, forward, outward, and backward; on fists with knuckles facing inward, forward, outward, and backward; on five, four, three, and two fingers and finally on the thumbs. Another traditional exercise is to stand in a sitting stance with the arms extending to the front and repeatedly close, squeeze, and extend the fingers rapidly for a few minutes.
Dan Hodge, Olympic champion and Oklahoma wrestling coach, noted for his incredible grip, strengthen his powerful grip by repeatedly crumbling sheets of newspaper into a ball with one hand. At his peak, he could crush a whole apple in one hand. As another exercise, try to fold a sheet of newspaper (or any size paper) in half more than seven times.
Grip strength comes from the ulna side (pinky side) of the hand. A boxer's fracture would significantly affect your grip. Try to hold anything with a handle without using your fourth finger. This means you will not be able to defend yourself by grabbing or gripping a weapon.
Another consideration is cutting the knuckles on the perpetrator's teeth. Punches are usually directed to the head area, but the mouth should be avoided. However, the teeth may be struck inadvertently. Humans have the very infectious mouths, including AIDS. Once you break skin, you are introducing all those germs to your body. When you open your hand from a fist, the tendons pull back. If the knuckles are cut when a fist strikes teeth, the act of opening the hand pulls bacteria in. Serious infection can set in within 24-48 hours. When a mouth strike is made with the heel of the palm, any impact with the teeth distributes the contact area making it difficult to break skin. With a punch, one knuckle may hit the teeth, breaking skin easily, because the skin on the dorsal side (top of the hand) is easily cut since it is very thin. The opposite is true of the skin on the palm. Germs do not fester as easily in the fleshy palm of the hand as they do in the knuckles. With a properly executed palm heel strike, the chances of injuring the hand are slim.