“The objects of the weave are (1) to make a moving target of your head (from side to side); (2) to make your opponent uncertain about which fist you will throw when you punch; and (3) to make your opponent uncertain about which way you will slip if he punches at you.
When you are using the weave by itself in your normal punching position, you must keep your shoulder movements slight. Otherwise, you'll open up your defenses.
However, the weave is rarely used by itself. Almost invariably the weave is used with the bob.”