Quem é o Lorde Sith que poderia transferir a essência e mudar para o lado da luz?

O Lorde Sith em questão era Darth Gravid .

A human Sith Lord whose short reign had elapsed some five centuries earlier, Gravid had been persuaded to believe that total commitment to the dark side would sentence the Sith Order to eventual defeat, and so had sought to introduce Jedi selflessness and compassion into his teachings and practice, forgetting that there can be no return to the light for an adept who has entered the dark wood; that the dark side will not surrender one to whom, by mutual agreement, it has staked a claim. Driven increasingly mad by his attempts to straddle the two realms, Gravid became convinced that the only way to safeguard the future of the Sith was to hide or destroy the lore that had been amassed through the generations—the texts, holocrons, and treatises—so that the Sith could fashion a new beginning for themselves that would guarantee success.

Uma citação posterior confirma que os Sith Lords (antes do Gravid) estavam rotineiramente na posse de conhecimento de como completar uma transferência de essência ";

Darth Bane had referred to sorcery as one of the purest expressions of the dark side of the Force, and yet he hadn’t been able to harness those energies with near the skill as had his onetime apprentice Zannah. Bane’s disciples, however, believed that he had experimented with a technique of even greater significance: that of essence transfer, which he had learned after acquiring and plundering the holocron of Darth Andeddu, and which involved the relocation of an individual’s consciousness into another body or, in some cases, a talisman, temple, or sarcophagus. Thus had the most powerful of the ancient Sith Lords survived death to haunt and harass those who would infiltrate their tombs.

O livro está falando sobre Darth Gravid . O livro realmente fornece seu nome em quatro lugares. É bem claro que Plagueis não pensa muito nele.

Plagueis reflete sobre a falta de domínio da Ordem Sith sobre a morte.

Sadly he could glean only so much from the texts, crystals, and holocrons stored in the library. Crucial knowledge had been lost during the brief mastery of Darth Gravid, and many of the most important elements of Sith training since had been passed from Masters to apprentices in sessions that had been left unrecorded. More to the point, Darth Tenebrous had had very little to say regarding death.

Plagueis e Sidious conversam sobre acabar com os Jedi.

SIDIOUS: "The Jedi won't simply stand by and do nothing, Master. While I have no affection for them, I do respect their power. And weakening the Republic without weakening the Jedi could provide them with justification for attempting a coup. They have the numbers to succeed."

PLAGUEIS: "There time is coming, Sidious. The signs are in the air. Their Order might have already been decimated had it not been for the setback Darth Gravid dealt the Sith. But his apprentice carried the imperative forward, and each successive Sith Lord improved on it, Tenebrous and his Master most of all..."

PLAGUEIS: "Your thoughts betray you. Do you think that Malak's powers were weakened by Revan's lightsaber? Bane by being encrusted in orbalisks? Do you think Gravid's young apprentice was hindered by the prosthesis she was forced to wear after fighting him?"

Sidious pensa no ciclo de um aprendiz matando seu mestre e depois criando seu próprio aprendiz que um dia o matará.

He (Sidious) sometimes wondered: Was he a level behind? Two levels behind? Such questions were precisely what had driven generations of Sith apprentices ultimately to challenge their Masters. The uncertainty about who was the more powerful. The need to test themselves, to face the definitive trial. The temptation to take the mantle by force, to put one's own spin on the power of the dark side--as Darth Gravid had attempted, only to set the Sith back countless years...