Shikigami

A Shikigami is a term used to describe familiars, who are created with a ceremony using the blood of the creator and different mediums. They act as familiars to the masters. The medium can be monster parts, different items or other materials.

Normally the creator can't change them later on, but heroes are able to adjust them even after they are created, using their legendary weapons.

List of known Shikigamis
There are only two Shikigamis mentioned: