Blood Demon Art

Blood Demon Arts are supernatural abilities and/or techniques possessed by higher-level demons.

Description
Every time a demon devours a human, the demon becomes stronger, and they can eventually develop unique supernatural powers, known as Blood Demon Arts. The power bestowed by the Blood Demon Arts is different from demon to demon that seem to be based around a central theme, (i.e. martial arts, sleep, the sea) some of which are seemingly based on a demon's past, personality, interests, and/or occupation. Moreover, Blood Demon Arts may not have a singular usage, and instead grant multiple abilities under the same concept or theme. As suggested by its name, all supernatural phenomena and effects use their wielders' blood as a medium to manifest themselves in reality. Essentially, Blood Demon Arts are blood magic.

The abilities and effects granted through Blood Demon Arts can vary greatly. Some can be combat-orientated (i.e. creating dozens of blades) or more supplementary and practical (i.e. controlling a fortress, manifesting illusions). Some are more simple and recognizable (i.e. manipulating electricity and ice), while some are more complex and unorthodox (i.e. creating invisible arrows that control a person's vector, controlling one's biology), thus making the abilities of demon-kind extremely versatile and powerful.

It is implied that Blood Demon Arts can be shared, as seen with Rui being able to share his spider-themed Blood Demon Art with demons in his "family", granting them Blood Demon Arts (as well as characteristics) based on spiders.

Blood Demon Arts are not to be confused with other supernatural abilities possessed by demons including but not limited to their regeneration, flesh morphing, extrasensory perception, and absorption abilities.

Weaknesses
A universal weakness to Blood Demon Arts is that they are susceptible to both sunlight and Nichirin weapons, meaning that they will disintegrate or be dispelled when exposed to sunlight or cut with a Nichirin Sword, possibly attributed to the fact that each ability and technique is created from a demon's flesh and blood.

Another weakness is related to the demon's blood, where if in some situation where their body's blood gets depleted, they will be unable to use their Blood Demon Arts. This is evident in Kokushibo being unable to unleash any crescent moon blades when Genya Shinazugawa's blood-sucking trees are holding the Upper Rank down.