Thieve's Garb
-aka-
Garret_Strife's Threads
This is true thief gear. Black shirt, black pants. Simple, functional, and always in style. You can get them from Sottilde at the Thieve's Guild in Balmora. And you can thank Garret_Strife for the idea.
The shoes seen here are a part of
Project: "Feminine Attire".