Rho'ha Displaying the Shaquarava in "Pandora's Box"
Shaquarava is both the name of a character from Taelon myth and also the name given to the vestigial organs on the hands of Taelons, Jaridians, Kimera, and various hybrids thereof that allow the bearer to release energy through the hands.
In Taelon myth, Shaquarava was the twin brother of Umrathama. Umrathama forced Shaquarava into a void but Shaquarava survived and returned stronger than before and full of rage. He turned that rage on his brother and defeated Umrathama ("Avatar"). This myth may predate the Taelons themselves; the Kimera and the Jaridians both use the term for the same organ (not to mention that the names do not conform to usual Taelon naming conventions).
On Earth, an imprisoned murderer named James Pike saw himself as the incarnation of Shaquarava. He saw Da'an as Umrathama and believed it was his duty to kill Da'an. He attempted an assassination and failed. Before he died, Pike told William Boone that he must take on the mantle of Shaquarava to protect humanity from Umrathama ("Avatar").
Later on, when Rho'ha revealed his shaquarava, it was revealed that the organ is named for the mythological character, although the precise reasoning is never explained. Rho'ha's shaquarava manifested after an experimental procedure in Taelon devolution, which had been developed by Ne'eg.