Alright, here i go, Into the eye of the storm.
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Darth Bane Vs Emperor Vitiate .
Lightsabers: Bane is a powerful and masterful duelist, practicing and mastering the ferocious Juyo form along with Soresu and Djem So. He is a powerful duelist defeating the likes of Kas'im who was considered to be the greatest of his era, he was capable of defeating the highly talented and amplified echani Jedi Master Raskta a extremely masterful duelist who was hailed as the greatest of her time. he defeated both of them. While many would low ball his fight with Zannah it should be noted that they trained for years together it would only be natural that Zannah have - at the very least, some idea of what her master would use against her. and it also should be noted that the only one to defeat Bane in a duel was the person he trained himself.
While i don't think Vitiate is a mook with the saber and could potentially hold his own against average and above average Duelists, I don't think he would be able to stand against Bane's mastery of the blade. So i'm giving the edge of sabers to Bane.
Force Powers. Vitiate is an incredibly strong sith lord, being both feared and respected by his entire empire. His power was so great that even the powerful jedi master and Sith Lord, Revan fell to him. A master of the Dark Side, vitiate could unleash a devastating Force Lightning storm that was able to disorient an entire Jedi strike team and cause Revan - a highly skilled practitioner of Tutaminis, to fall and struggle against the lightning. A master of sith alchemy and sorcery vitiate was proficient with the use of powerful Rituals and due to one such ritual caused the devastation of Natheema which shook the jedi Exile - Meetra surik. a master of the force Vitiate is a powerful force to be reckoned with.
I won't bother with Bane's force feats as we all probably have them memorized from the constant debates and threads that appear nearly everyday.
Now while, i consider Bane to be an extremely powerful force user, who is match for nearly all of the top sith lords. This is one that i think has no definite winner. both are extremely powerful and have a great variety of powers at their disposal. but i feel a force fight between these two is too difficult to judge. So in my opinion these two are equals in terms of force powers and a fight between them with only FP can really go either way. but this is just my opinion.
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Zannah Vs Revan?
Lightsabers. This goes to Zannah, before her No one was able to best her master in a duel. Legendary and powerful masters fell to him and she was talented enough with the blade to have held him off and beaten him. Revan while not a mook with the blade, he has not defeated someone on the same level as Darth Bane and if he fought with someone, it remains unknown if it was mainly a Duel. He's a skilled duelist, yes. and his precognition is powerful, however he lacks the same strength that many say Zannah had difficulty.
Zannah takes Sabers.
Force Powers. Both are highly talented with the force. Like with Vitiate, Revan is highly strong in the force being considered "the heart of the force" by his former master. Like I said with vitiate and Bane, Both them are extremely powerful and talented. I feel that Revan is above Zannah due to his greater variety of powers. However he isn't above her by much, as Zannah has her illusions to compensate for her lack of variety. That said, i think a force fight between the two could really go either way, as regardless of who you think wins, it will be a very hard fight.
All-out. I say Bane and Zannah take it, but Vitiate and Revan give them one hell of a fight. however this is really Just my opinion.