Sacred Artifacts are objects that are primarily used as a medium through which a transient or human can display their abilities. They can be used to impose the Rule with which it is associated with and affect the regular world's laws of nature. The Sacred Artifacts, just like many other mechanics in the Game, only work properly within an enclosed space such as the one created when an App Battle occurs.
The Sacred Artifact is usually an object, instrument, weapon, or even body part associated with the being that it was summoned with. For example, the sword Sacred Artifact Moritaka carries is the Murasame, a special type of sword that the character Inuzuka Shino Moritaka uses in the novel, Nansō Satomi Hakkenden, where the character originated from. With native humans, the Sacred Artifact they carry is often given to them when they summon a transient but they were placed in an unknown space due to the dangers they pose to the game. For example, the tome Sacred Artifact Shiro uses is the Necronomicon, a book that was created by a follower of Yog Sothoth.
The Sacred Artifact may appear to look like anything that a being may have in possession. The artifacts all vary in shape or form, it can range from weapons such as swords and bows to mundane objects such as a hat, pillow, or book. Some are even incorporated into or are part of a being's body like for example, Melusine's Sacred Artifact is her dragon wings or Kagutsuchi's artifact is his blood. Some artifacts can even be considered fully alive such as with one of Hephaestus's Sacred Artifacts being the automaton Talos.
There is currently no limit to how many Sacred Artifacts a being may possess but the majority of the known beings usually just have one with Ebisu currently having the most with three (just two if excluding the sail artifact he got in the Make Sail event).
The artifacts have been described in the story as being composed of Dark Matter, a substance that has the ability to contain rules, memories, and information inside of them. The guild Crafters have been studying this matter and often use them for experiments that usually involve the artifacts, such as creating or repairing them.
The Sacred Artifact is often tied to a particular Rule with which the artifact itself may act as a medium to release the ability associated with their respective Rules. The tie of the Rule and the artifact is not solid and can be traded for another as seen in the Raiders of the Lost Isle.
Sacred Artifacts, through Dark Matter, can contain the memories and information of the past but due to how the Game functions, the Dark Matter's information is usually wiped clean when a reset occurs. Pillars are special types of Sacred Artifacts that can retain the memories and information stored in them even after the event of a reset. They are usually separated into two categories, Complete Pillars are those that can retain all memories and information inside them while those that retain specific types of memories, usually associated with an event or emotion, but nothing else are called Incomplete Pillars. Examples of Incomplete Pillars are the Sacred Artifacts of Surtr, whose helm can only keep the memories of anguish; Horus's pillar can only retain the memories of betrayal; while Azathoth can only retain the memories of ends that preced a loop reset.