1.He was a big fish in a small pond.
2.He got all of his tactics from the mandalorians and the Sith way of doing things, he used his number of Jedi and greater army of troops to overwhelm them, not all that impressive when you really consider it.
3.You said it yourself, he was retrained into the Light Side, his new identity, the old one still had all of his previous power, Kreia also said the Exile was her greatest student and all modern day Jedi are nothing compared to the ancients, Jolee Bindo also stated that Revan and Malak were basically Sith wannabes compared to Exar Kun and Ulic-Qel Droma.
4.It's against G-canon, get to grips with that and move on, Drew's attempts to make his baby the next best thing to the Chosen One failed, he can't beat Lucas or Chee, simple, hence we know that he achieved oneness with the force, due to the description being pretty much exactly the same to the description gave for when Jacen Solo achieved oneness with the force.
Now what does Revan have that poses a significant threat to Vader, Bane or Kun? exactly, what does Vader, Bane and Kun have that would pose a serious threat to Revan? a hell of a lot.
What do you mean beat Lucas? I never said Drew's novel was good (although I did enjoy it). The fact is, Drew's book got published and thus it should be reckonized as Star Wars fact, regardless of what you think about his writing.