Originally posted by Revolver Ocelot
The leader of the Sith in the most warlike time in Star wars history (Kaan) was scared shitless of him. We may not know much now, but no doubt he's powerful.
This is in a sense misleading, but it's on the right track. Bane was pretty powerful, he lived in a time when sith fought jedi all the time, and with his symbiotic armor he's resistant to the blade.