Anyway, I deleted the mesh file from my meshes folder. That... didn't work. For some reason, it's still shiny.
So, I have two questions here: One, which mod did it, and two, how do I either get rid of it or get the reflective map to ALL Ebony armor parts? Don't mind the reflective map... it just sticks out like a sore thumb when the rest of the armor doesn't have the map! Note that the mesh has been otherwise unchanged; it looks like a vanilla Ebony Cuirass, but reflective.