The Arrin-thar is a Kencyr fighting discipline using clawed hands; a practitioner is called an Arrin-thari. Some Shanir have natural claws and are called natural Arrin-thari, but the Arrin-thar can also be performed with clawed gauntlets by those without natural claws.
The Arrin-thar is a Shanir based fighting discipline; that is the Arrin-thar is the fighting discipline of the natural Arrin-thari and full use of it practices, that is the magical effects it might produce, is likely restricted to the natural Arrin-thari. As a Shanir based fighting discipline the Arrin-thar is frowned on by the majority of the Highborn. It is the only Shanir based fighting discipline, that has been mentioned explicitly, though there are other Shanir based fighting disciplines.