ARM IK Blending
Blend - This value will blend between Forward Kinematics and Inverse Kinematics for the Arm System. There are actually 3 separate Arm systems in play. A FK system that is driven by the UpArm, LoArm and Wrist rotational spinners, a IK Arm system that is controlled by a multiple target blending system and the Arm system that Blends between the FK and IK systems. The FK/IK Blended Arm system is the one you see displayed in the viewport. A Value of 0 gives you the FK system while a value of 100 gives you only IK.
Swivel - this will adjust the swivel angle of the IK Arm system, thus rotating the elbow.
Wrist - this will align the wrist to the end target of the IK system.