When trying to assassinate NPC in Fargrave the Blade of Woe doesnt seem to work there.
Its normal, non-essential NPCs like house owners but i cannot seem to oneshot them.
You cannot kill Daedra with the blade of woe, only humanoid species.
I guess you never played the main questline, or visited Coldharbour or the Imperial City for that matter. Dremora can be killed by the Blade, Xyvkin (ad goblin-kin) cannot.
The blade of woe works on humanoid dremora in other zones including overland blackwood and seemingly all other daedric realms
All except Fargrave and the deadlands as well as Blackwoods deadlands doomvaults in the deadlands anchor side
so when you enter a doom vault and find a dremora you can kill him with the blade of woe untill you get too far in and are on the farthest deadlands side. WHY?