Ifrit.Eikechi said:
Uriel Blade is Fragmentation based.
Asura.Cruxis said:
In Necropolis when I did it was Atonement > Uriel Blade = Light.
EDIT: Reportedly Light primary and Frag secondary, actually. See wiki commentary. Not that you'd usually notice the Light property unless you were looking for it, this is Campaign after all...