Malak turned Bastila to the darkside because she was an inexperienced Padawan who had yet to properly handle strong emotions. It wasn't that the torture itself that broke her, it was the fact that Malak made her realize the power that all that pain and anger gave her. Also, Malak grew stronger as he became Dark Lord of the Sith. I'm inclined to think that Malak did surpass Revan, only to be surpassed in turn by him. He does say that Revan was stronger near the end of Kotor I than he ever was as a Sith Lord.
"I suppose… I suppose you speak the truth. I alone must accept responsibility for my fate. I wanted to be Master of the Sith and ruler of the galaxy. But that destiny was not mine, Revan. [cough] It might have been yours, perhaps… but never mine. And in the end, as the darkness takes me, I am nothing."
I think that's pretty weak from a Dark Lord of the Sith.
The non canon DS ending is even worse
Yes. I cannot deny it any longer. You are the one who deserves... who deserves to be the Dark Lord. You were the one who found the first Star Map on Dantooine, Revan, and it was you who led us on our quest for the Star Forge. I only followed in your wake. I tried to usurp your rule, to steal the title of Sith Master from you. But now I understand. The destiny is yours Revan. Not mine. You... you are Darth Revan, Lord... Lord of the Sith. And I... I am nothing.
What the heck is that? It's just disgusting to hear from any Sith, not to say a Dark Lord of the Sith.