I don't fully recall where, and I haven't accually done it myself, but I'm pretty sure you
can find the Daedric Dia-Katana in an Egg Mine in a general area in some place in Molag
Mar
But I do know how to find it. You go into the mine towards the back, and then try to find
a sort of hill, if you happen to do so, climb over it. There should be a dead person named
Dead Man, or something like that. He should have the Deadric Dia-Katana. But remember, I
haven't done it myself yet, so don't get your hopes up. Hope I could help.
(\___/)
(='.'=) This is Bunny. Lol.
(")_(")
Again, I hope I could help at least a bit. . .