Yeah i always figured Bandon was weak too, but if you listen to what is said about him, read that thing about him on the Kotor side and see what he has accomplished you can't really think that he is weak anymore.
Afterall he was the apprentice of the Dark Lord, who could choice from thousands of apprentices and would logicly choose the most powerful one.
If there was somebody more powerful then Bandon, he/she would have just killed Bandon and taken over the role as apprentice.
Bandon is said to have killed many Jedi with his lightsaber and has not met an opponent that could beat him. Not that, that means he can't be beaten though. Just not by the Jedi he has faced, and seeing as he is the apprentice of the Dark Lord those Jedi were probably pretty powerful on their own.
I always thought Bandon was weak, but after considering all of that shit, i have come to conclusion that he is indeed quite powerful. Probably more so then Maul. Afterall from what i can tell he has faced more opponents and probably a few powerful one's too