The ONLY legit weapon that could come close to matching the damage of an Ith, would be an ethereal Cruel Colossus Blade of Evisceration (300/65), and that's still a good 150 points of max damage short. The Ith also hit max WW breakpoint too, whereas that Cruel wouldn't be near that.
Well, statistically the Ith had everything better than the fbb. Only thing about that sword was the ignore target defense. That made that sword fucking awesome. Load up on leech, and you were unstoppable with that sword. I don't know the statistics of it, I just know I whooped some barb's asses with that sword.