You aren't wrong about Revan, he was described as a maelstrom of the force by Kreia and he was one of the greatelst military in history he nearly conquered the republic but was stopped by his apprentice betrayal, he saved the galaxy twice, from the mandalorians and from his mistakes and i believe he could had defated if wasn't by Scourge. He survived 300 years of physical and mental torture and he actually splitted himself in two embodied personalities of himself.Vader is powerful but not invencible.