One of those robots was more then powerful enough to kill a Jedi Master.. Revan faced dozens at once.
About Visas being powerful, thats crap.. She wasn't, she was the apprentice because she was blind and saw through the force. she could see things that others could not. Nihilus did not need a powerful apprentice, he needed one that could help him with stuff that he could not do himself. See.
About the Exile getting his power back, yes he got it back when he picked up Nihilus his mask... Which brings me to the following point...
Kotor II if finished would have been something like this
intro: Revan walks up to kreia "Go find a way to kill Nihilus" "okay"
game happends
Exile kills Nihilus and follows Kreia to Malachor, where he either kills her or works with her to kill his friends. Either way after that Revan shows up and beats the crap out of you.
Remember that cave on Korriban, that one shows the story as it was supposed to be, the only difference is though that Revan there isn't immortal. Every opponent you face in that cave except the real one's can be killed in one strike. Revan however needs more then one, Revan was amazingly powerful and if Kotor II would have been finished, he would have owned the Exile's ass at the end of the game.
But lets just say that was never the intention for the game then its still a matter of putting facts together.
- The Exile has killed what four Jedi Masters at most, plus three Sith Lords from which only one was impressive. The Exile and Nihilus were still the same, you can't ignore that. And Sion wasn't powerful he was just hard to beat.
- Revan had more Jedi Masters then that serving under him during the Mandelorian and Jedi Civil war. He has killed far more Jedi then that, and faced a lot of the most powerful Jedi alive at that time.
- Kavar who was one of the hardest masters to beat in the game, second to Vrook. He admits himself that he easily lost to Malak. Revan his apprentice.
- The Exile followed Revan, he was never Revan. He did not learn the teachings of the Jedi and the Sith, he was just a general. A tactician. Not a military genius.
- The only thing the Exile did what was really impressive was killing Kreia, killing Revan his former master. Kreia however admits that she was weaker then Revan. Sion also says Revan is stronger then Kreia. So that is not something Revan could not have done.
All in all, the exile has done nothing Revan could not have done, and most of what he has done is far less impressive then what Revan has done... And thats just considering the unfinished game.