Origem do Vaapad?

TL; DR Ambas as respostas estão corretas, já que as diferenças derivam de um detalhe técnico. As citações relevantes são:

Vaapad is as aggressive and powerful as its namesake, but its power comes at great risk: immersion in Vaapad opens the gates that restrain one's inner darkness. To use Vaapad, a Jedi must allow himself to enjoy the fight he must give himself over to the thrill of battle. The rush of winning. Vaapad is a path that leads through the penumbra of the dark side.

Mace Windu created this style, and he was its only living master.

A vingança da novelização Sith , página 329

Wookiepedia tem esta citação listada:

I created Vaapad to answer my weakness: it channels my own darkness into a weapon of the light. (Mace Windu to Obi-Wan Kenobi, Revenge of the Sith novelization)

Mas, de acordo com uma pesquisa no Google, ela não existe no romance.

Do livro Shatterpoint , dito por Yoda:

Six there were for generations of Jedi. The seventh, is not well-known. Powerful form it is. Deadliest of all. But dangerous it is, for its master as well as its opponent. Few have studied. One student alone, to mastery has risen.

Deve-se notar que houve tecnicamente duas variações de Formulário VII - Juyo e Vaapad. Juyo era a versão mais antiga, ensinou com moderação, mesmo assim entre os Jedi e depois caiu em desgraça. Vaapad foi "redescoberto" por Windu, junto com Sora Bulq . O artigo wookiepedia sobre isso tem a dizer (originado):

the mastery required to learn Form VII was such that only a select few would be allowed to utilize it; he forbade its study to all others. At least two users of its Vaapad variant during Drallig's tenure described the form as dangerous due to its focus on physical combat and intensity. For his part, Drallig refused to allow Anakin Skywalker to study Juyo, while Obi-Wan Kenobi was likewise forbidden to learn Vaapad by Qui-Gon Jinn.

...

Jaric Kaedan, a Jedi Master who fought in the Great Galactic War, was a master of the form—which was known as Juyo-Kos by that time—and he was considered a living weapon guided by the will of the Force itself. Another Great Galactic War combatant, the Sith Lord Scourge also employed Juyo...Another Sith Lord of that era, Darth Bane, was proficient in the use of Juyo.

Quanto ao motivo pelo qual o termo Vaapad aparece em Darth Bane , há isto:

The Sith apprentice Sirak in Darth Bane: Path of Destruction was stated to be a Vaapad practitioner, long before the style was created by Mace Windu. At a book signing in Huntington Beach, California, author Drew Karpyshyn said, "I meant Juyo, but it was a late night when I wrote that and didn't catch it until it was too late. That's one mistake I wish to God I could change. So when you read it and see 'Vaapad', just pretend it says 'Juyo.'" Star Wars Insider 92 later explained it by stating that "juyo" was another term for the vaapad creature the form was named after.

Esta seção do artigo tem mais informações sobre as diferenças entre Juyo e Vaapad.

O livro " O Caminho Jedi " tem uma "nota manuscrita" de Obi -Wan Kenobi na página sobre o Formulário VII - Juyo:

Master Windu has developed a variant of Form VII called Vaapad.

Isso sugere que, embora a Forma VII original tenha sido chamada de Juyo, Mace Windu desenvolveu o próprio Vaapad.

Depende de qual cânone você deseja seguir.

De acordo com Wookieepedia :

G-canon is George Lucas Canon; the six Episodes and any statements by George Lucas (including unpublished production notes from him or his production department that are never seen by the public). Elements originating with Lucas in the movie novelizations, reference books, and other sources are also G-canon, though anything created by the authors of those sources is C-canon. When the matter of changes between movie versions arises, the most recently released editions are deemed superior to older ones, as they correct mistakes, improve consistency between the two trilogies, and express Lucas's current vision of the Star Wars universe most closely. The deleted scenes included on the DVDs are also considered G-canon (when they're not in conflict with the movie).

T-canon, or Television Canon, refers to the canon level comprising the feature film Star Wars: The Clone Wars and the two television shows Star Wars: The Clone Wars and the Star Wars live-action TV series. It was devised recently in order to define a status above the C-Level canon, as confirmed by Chee.

C-canon is Continuity Canon, consisting of all recent works (and many older works) released under the name of Star Wars: books, comics, games, cartoons, non-theatrical films, and more. Games are a special case, as generally only the stories are C-canon, while things like stats and gameplay may not be; they also offer non-canonical options to the player, such as choosing female gender for a canonically male character. C-canon elements have been known to appear in the movies, thus making them G-canon; examples include the name "Coruscant," swoop bikes, Quinlan Vos, Aayla Secura, YT-2400 freighters and Action VI transports.

S-canon is Secondary Canon; the materials are available to be used or ignored as needed by current authors. This includes mostly older works, such as much of the Marvel Star Wars comics, that predate a consistent effort to maintain continuity; it also contains certain elements of a few otherwise N-canon stories, and other things that "may not fit just right." Many formerly S-canon elements have been elevated to C-canon through their inclusion in more recent works by continuity-minded authors, while many other older works (such as The Han Solo Adventures) were accounted for in continuity from the start despite their age, and thus were always C-canon.

N is Non-Canon. What-if stories (such as stories published under the Infinities label) and anything else directly and irreconcilably contradicted by higher canon ends up here. N is the only level that is not considered canon by Lucasfilm. Information cut from canon, deleted scenes, or from canceled Star Wars works falls into this category as well, unless another canonical work references it and it is declared canon.

D is Detours Canon, used for material hailing from Star Wars Detours.

A maior parte da novelização do episódio três cairia em G-Canon , mas como Vaapad não é mencionado nos filmes finais, essa parte cairia em C Canon . Os romances de Darth Bane cairiam sob o C Canon por padrão.

Como ambas as partes dos livros em questão estariam sob C Canon , nenhuma delas é necessariamente "mais correta" que a outra.

Baseado na entrada de Wookieepedia em Vaapad , Darth Bane é um praticante de Juyo - uma forma inicial de Vaapad. Não há citações referenciadas de Vaapad nos livros de Darth Bane no artigo. Se este for o caso, não há conflito em quem a criou.