 So you got a classic case of twisty arm, not a problem. Now you can solve this problem by adding new points and creating shape keys but that would require you to create two shape keys. One for when the hand rotates 90 degrees and one for negative 90. But there isn't an easier way that only requires one extra bone. In edit mode, add a bone for the wrist and make sure that it's parented to the forearm. In white paint mode, give the wrist bone greenish yellow control of these points here. Then in pose mode, add two copy rotation constraints. Both of them should set target to armature, bone to hand, and local space for all. Make sure the top one only checks Y and is set to about 0.6. The bottom one should only check Z and should be about 0.37. If you twist the arm now, you'll find that most of the problem has been fixed. But you still have the issue of bending up and down looking weird. Now the easiest way to address this problem is with the driver that moves the points back and forth based on the hand Z rotation. To do that, in pose mode, click the wrist and in the bone tab, right click the variable that controls moving left and right. In my case, it's Y location. Edit driver, object to armature, bone to hand, type to Z rotation, mode to quaternion, space to local, and type this. And you're done. Now you can see that the bone travels back and forth based on the hand Z rotation. Hope that helps. If you enjoyed this video, please don't forget to like, subscribe, and ring that bell. Hope you have a fantastic day and I'll see you around.