The Sentinels were once the judiciary system of the Nessi. They regulated and dealt with any that varried from the path chosen by Etarl Arioch in a negative fashion choosing to destroy. They also hunt those afflicted by corruption.
The sentinels had four branches to replresent Elyss’s Compass
The Seed withing the Shield – Also known as a priest/priestess for lack of translation. They were the operations control/think tank. Example Faye
The Hearted Bow – Collectors of powerful artifacts that they would store in a remote location. Example James Faulconer