Mentioned in the book
The Dark Spirits by Amun-dro, the Silent Priest
Not too bothered about the black panther (the year of Azura's cats is all but over). The hidden sword is Mephala's Ebony Blade, I assume (it was hidden behind a locked door in TES V).
But, who do you think is "a warrior in ebony armour"?
The reflex answer is Ebonarm, but a little thought shows that it must be wrong. Ebonarm doesn't work for the daedra, he's more of a peace maker than a spirit of vengeance, and it also looks like he has been retconned out of existence in ESO already anyway.
The Ebony Mail is Boethia's boon. So who is wearing it? Are we being primed for something in U26? Ebony kind of fits with gloom, nightfall, and gothic.
Maybe Darien has found a new mistress. This would certainly make him appear different to when we last met him.
edit spelling
Edited by RaddlemanNumber7 on November 28, 2019 2:53PM PC EU