Blood Demon Art

Blood Demon Arts are spells or techniques that higher-level Demons can cast. The specifics of these spells are unique to each Demon.

Description
Every time a Demon devours a human, the demon becomes that much stronger, eventually developing special, superhuman powers, known as Blood Demon Arts. The power bestowed by the Blood Demon Arts is different from Demon to Demon, and in some cases, Demons are able to use more than one special superpower.

However despite this ability being exclusive to the Demon Race, it is also possible for a human to use Blood Demon Arts by consuming the flesh of Demons, effectively turning themselves into "Pseudo Demons". This is seen with both Genya Shinazugawa, who excessively ate demon flesh during his time in the Demon Slayer Corps and obtained flesh manipulation abilities and later obtained and created his own Blood Demon Arts after eating the flesh of Upper Moon's One & Four and a previous Demon Slayer who battled and was killed by Kokushibo 300 years prior to his death.

The abilities achieved through Blood Demon Arts can vary greatly. Known examples of these various powers include, but are not limited to:
 * Generation and/or manipulation of natural elements.
 * Alteration of their physical body.
 * A power up transformation.
 * Merging their own body with a preexisting object.
 * Detachment of their own flesh to create and control another entity.
 * Casting Illusions.
 * Putting others to sleep.
 * Exerting control over a preexisting structure.

Weaknesses
Due to the sheer variety of different unique techniques, powers, and abilities a demon develops as they grow stronger, each Blood Demon Art possess their own unique weaknesses and no two techniques or powers are the same.

However a universal weakness to these powers is the fact that they are susceptible to both Sunlight and Nichirin Blades due to the fact that each technique is fundamentally created from using a demon's flesh and blood, and similarly, the matter created from these techniques would also likely disintegrate once exposed to sunlight and be dispelled or weakened if a Nichirin blade cuts it.