This quest is not available in game.
Get Catelyn's dagger from "Pretty Boy" Duncan.
My FATHER sent you? I'd have thought that old codger would have given up on me by now.
It wasn't really his fault I ran off, he just shouldn't have expected I'd be willing to live a boring life, reading over musty books and associating with grey-haired, stiff-backed, stuffy mages!
If you need my dagger, you'll have to get it back from "Pretty Boy" Duncan, one of the Bloodsail Buccaneers. Put something 'tween his shoulders and I'm sure he'll give it up.