How could he have been better?
Use his Wizards of the Coast D20 rules implementation, being a Jedi Guardian 11/Sith Lord 9 (or close fudge thereof) with more powers and stronger powers than his normal level allows, rather than just a Guardian 20 with super-high stats.
And take out those Jedi-in-a-can health packs of his, cause killing him nine times because you didn't take the 'right' powers is tedious. (Note to devs: If TSL does anything like that, I am gong to hunt you down. I know you can hear me. If you thought Carth suffered around here, you ain't seen nothng yet...)