Shards are demon powers that have been crystallized. While normally cannot be handled, special persons like Miriam could absorb and utilize the crystals to use special abilities corresponding to the shard's source by impaling the Shards to their bodies. These special abilities range from "active" abilities like shooting fireballs, "passive" abilities such as double jumping, to "reactive" abilities such as summoning guardian familiars.
So far, there are six types of Shard, each of them having their own special traits and are color-coded.
Trigger Shards are basically magic attacks, that Miriam could launch to enemies in front of her. Trigger Shards are color-coded red. One example of a Trigger Shard is the Cerulean Splash.
Currently, there's no more info on this type of Shard.
This type of Shard lets Miriam cast magic attacks toward a flexible direction, which can be adjusted with the controller. Directional Shards have purple color. An example of a Directional Shard is the Fire Cannon.
Enchant Shards give Miriam various benefits while being equipped, such as an increase in a certain combat stat. They are yellow-colored. An example of Enchant Shard is the CON Booster.
This type of Shard give Miriam the ability to summon Familiars. Once summoned, the familiars will help Miriam in various ways, such as attacking enemies in close proximity of Miriam. Familiar Shards are colored green. One such example of this type is the Dullahammer Head.
This type of Shard grants Miriam passive abilities. Skill Shards take effect automatically, so they don't need to be manually equipped. Skill Shards have white color. An example of a Skill Shard is the Double Jump.