In their true form demons look almost nothing like humans with large red bat-like wings, a pointed tail, tentacles on their head, long talon like claws, goat like feet and blood red skin. However, while possessing a human they look almost the same as that human making them extremely different to tell apart from that same human, however hunters have learned to notice several small differences caused by demonic possession, similar to fausts. Most of the major differences happen in the eyes, their pupils often grow and look quite dilated, the black lines in their eyes become much thicker and their eye color darkens to almost a blackish color. Their ears also begin to develop a small point, and if you look at their teeth they also begin to sharpen. The largest and most noticeable difference is their fingernails, as they seem to not stop growing and develop a razor-sharp edge. Black horses bow when a demon walks by, another reason that hunters often ride the steeds.
Demons are invulnerable to anyone but other demons and mages while under a Faustian Contract, however without a contract they do have a few weaknesses. The seven demon blades however, hidden throughout the world are the only objects that can truly kill a demon.