It depends on how your weapons system is setup, In mine the weapon is a separate actor with it’s own skeletal mesh. I would add a bone to the weapons skeleton that is parented to the root and is moved to where the left hand is supposed to be. Then in the engine I would add a socket to that bone on all the different weapons and use the same name for all sockets. Then it’s just a matter of getting the socket’s location and putting that value in the two bone IK node.