I created an arm IK with wrist control and elbow pole vector constraint. The IK's effector is moved from the forearm joint to the wrist. The wrist control has constraints for the Z axis on the forearm and X and y axis for the wrist joint.
It's a pretty standard IK rig.
It seems the closer the wrist gets to the shoulder (the more bent the arm is), the hand seems to twist irregularly (which doesn't follow the wrist controls orientation)
