USSEP adds the WeapMaterialDaedric [KYWD:0001E71F] keyword to the Blade of Sacrifice that you get for Boethiah's quest. To me it seems like the weapon should have ebony keywords. It is tempered with ebony, looks like ebony and it doesn't seem like it is of daedric origin or all that special (it is available multiple times and you don't need to use it during the quest).
The weapon also can't be enchanted even though it seems like it is just a normal dagger.