The Weave is a variation of the
423 in which a ball is carried through pattern by the hand that would
otherwise remain stationary. This motion can, if performed skillfully, make
the Weave one of the most graceful and elegant three ball patterns.
To begin learning the Weave, start with two balls in your non-dominant hand and one ball in your dominant. Cross your non-dominant hand over to the dominant side of your body, and then position your dominant hand above your non-dominant hand such that your arm is bent upward. Make a throw from your non-dominant hand back toward the non-dominant side of your body while simultaneously swinging your dominant hand up and over toward the center of your body. The thrown ball should pass along the outside of your dominant hand, which will in turn move underneath the ball and then swing back down to its normal Cascade position (the overall path of the hand should be an "S" shape). As your dominant hand is completing its motion, the thrown ball will be approaching your non-dominant hand, which should have shifted back over to the non-dominant side of your body. Make a relatively short throw from your non-dominant hand toward the dominant side of your body, clearing space for the first ball to be caught. The ball just thrown from your non-dominant hand will then be caught by your dominant hand.
As shown, practice this step on both sides. You will want to be very comfortable with the arm flourish, as it forms the backbone of the pattern. Next, you are going to perform all the throws, catches, and movements of the previous step, but instead of stopping after the second throw from your non-dominant hand you are instead going to raise your non-dominant hand up and catch the first ball a little higher than normal. You will then continue this vertical motion as your dominant hand crosses over to the non-dominant side of your body. At this point your non-dominant hand should be positioned above your dominant hand, mirroring the position you first started in. You will then perform the first step again, this time using the opposite hands.
You've now completed two cycles of the Weave. To perform the full pattern, simply keep doing cycles on alternating sides of your body. The Weave is a very cool trick in its own right, but it can also serve as a foundation for a wide number of variations, mostly by altering the shape of the arm flourish.