As its name suggests, the aspyrixis is related to the spyrix, but they are not identical. In contrast to spyrixes, which attract spirits through their function and consume their mana, an aspyrixis is predominantly a medical tool used to provide functionality to the body parts of disabled humans. They are small, palm-sized devices operated by a particular type of fossil bearing mana. Due to the fact that the mana escapes quickly as soon as it is dismantled, these fossils cannot be mined and transported, with the patient needing to be nearby so that the aspyrixis can be created and immediately applied.
Once applied to the body, the destroyed nerves of the region are stimulated, which results in tremendous pain for the patient, some even going so far as to say they would rather be left paralyzed than endure the pain. Even after application, it can take months of physiotherapy in order for the destroyed body part to regain its functionality completely.
In Tales of Xillia, Milla Maxwell loses control of her legs during an incident at Fort Gandala, leaving Jude Mathis and Leia Rolando to help retrieve a fossil for aspyrixis application, which proves to be successful. After her human body decays and she is reborn as a spirit, she no longer requires the device. In Tales of Xillia 2, Rideaux Zek Rugievit states that he was a sickly child treated with aspyrixis during his youth, the operations being carried out by Jude's father, Derrick, who actually developed the aspyrixis, enabling Jude to assist Milla with the technique in the prequel.