What I know of Nailah's Robes is not much, but perhaps it will
help lead you to them. I have heard a few rumors that one of the
groups of Mau had the Robes but I do not believe them. I have
heard more rumors that the Robes are in possession of the setians.
I will leave you to choose which rumors are true, but my instinct
tells me it is the setians.
The one with the robes will wander around
The Fortress of Storms from town to town.
Catch him unaware and bring to him the fight.
If he sees your approach then his choice will be flight.