Originally coined by Linelian Fareyes in his widely distributed On The Scourge of Acaesura, the term "volta" is retronymic. It was created out of literary convenience rather than in reference to a power or political designation.
The title has only ever been attached to three individuals: the dragonborn Palasar Tolthik of Highscale; the tiefling Inibis Valmeia of Necine; and the dark elf Taslyn Cordaer of Shade. The Three (as they are sometimes called) represent cardinal factions in what Linelian--and Acaelica at large--has come to call The Ascension War.
"Volta" is a word meaning "the turn," and more specifically, "the turn of thought or argument." The name was chosen with respect to a poetical motif that Linelian maintained throughout his seminal work.
It was the author's contention that these individuals represented three possible and incompatible turning points in the Acaelican "story."