So, while playing Dragonborn I noticed those altars you can find in Apocrypha had some daedric text. I'm talking about this:

http://galeon.com/yagare/tpf/altar.jpg

Yesterday I was bored, and decided to translate it. I was expecting something related to Mora, but the resulting text reads as:

THE WEAK SHALL BE WINNOWED THE TIMID SHALL BE CAST DOWN

Which is taken from Mankar's speech about Dagon's return, heard during the quest to recover the Amulet of Kings from the caves of Lake Arrius. Maybe Bethesda has decided to turn it into some kind of Daedra motto?

Cool find!

IIRC, that is from Mankar's speech but he was quoting the Mysterium Xarxes which I think is Dagon's words.

Actually the Mysterium Xarxes are all derived from the Oghma Infinium which was made by Xarxes from knowledge gained to him from Herma-Mora, Xarxes gave Mehrunes Dagon the Infinium in which Dagon read and used to write the mysterium xarxes.

Awesome find.

And yeah, this basically explains it.