>Yveltal's appearance is based on an avian in the shape of the letter Y. It may be based on the giant Hræsvelgr, or "Corpse Swallower," which takes the form of an eagle and sits at the end of the world, creating wind as it flaps its wings.
SnivyGunner is right, Hraesvelgr does come from Norse mythology. It seems like it's based on the Hraesvelgr, but Yveltal does hope for destruction.
It isn't exactly the 'Devil Pokemon', since Giratina is thoroughly based on the devil, as proved by some video I saw a while ago.
It seems that it originating from the Hraesvelgr makes sense, but we don't really know for sure. To answer your question, it isn't 'The Devil Pokemon'. It's evil, that's for sure, but it's not the devil Pokemon - that's Giratina's job. x)
Hope I helped. :)