The Closed Fist is an essence gem which grants a large bonus to Body and a moderate bonus to Spirit. As its name suggests, it is exclusive to followers of the Way of the Closed Fist — there is no exact equivalent for the Way of the Open Palm, with the closest counterpart (called The Open Palm) affecting different scores. It is not the same as the gem called the Way of the Closed Fist.
In-game description: "A master of the Closed Fist is a force that changes the face of destiny to suit his will. Those who seek the ways of power will always remember such strength of purpose. A fearsome force in body and spirit, this path brooks no deviation. the slightest weakness in a master of this caliber will be his downfall. Those who change fate accept no failings."