Theatrical arm

An arm movement commonly used by actors and singers.

Extend your arm forward with a bend of about 90 degrees at the elbow, so that the hand is level with and to the side of the face.

Now, bend the fingers into a claw-like formation, as if grasping something invisible.
Hold the arm in this position, thrusting the forearm forward to emphasise various words as often as necessary.

He was a serious actor. You could tell by the theatrical arm movements.