Well, at SL120 I have it up to 434 ar. Used a hollow infusion with 35/30/40 Str/Dex/Lck. For reference, a refined longsword with 40/40 Str/Dex is 428. The downside to the Hollow *** is it costs a lot of points into 3 stats to attain that ar at SL120. One upside though, is the *** uses less stamina than all the other popular SS's, and the Hollow infusion of course gives +5 luck, mitigating the 12 Fth requirement.
At SL 135 40/40/40 it would be 454 ar, it would beat out most of the other SS's as it scales well with LCK.
In short, it's not as bad as people make it out to be. At higher SL's it can actually reach a higher damage ceiling than most other SS's. But it takes high investment, making it terrible at lower SL's where each stat point is precious.