If you go into the Barcelona Sewers and look around, you should find a wooden lift, down there is where all the Thieves are. One of those might have the sword, if not them, try the Wererats on the eastern side of the Sewers, I think one of them might have the sword, of course, you may want to complete any quests you have with either side, before klilling them all off to get that sword.
Good luck.
