Doesn't it sound a lot like some sort of dragonborn?

I think it might be tied to the Akaviri dragonguard, the forerunners of the Blades. This time period has a lot of Akavir influence so it'd make sense.

Have you never saw someone that can leap with demonic wings in skyrim?

They are influenced by the Akaviri Dragonguard.

@Navh they wouldn't be demonic wings they are draconic. Thats why they are called DRAGONknights not Demonknights.

I'm talking about all the mention of dragons regarding the class.

Just because something is influenced by dragons doesn't mean that it has to be dragonborn related. The Akaviri were really influenced by dragons and they weren't dragonborns.

Could the akaviri breathe fire too?