After The Temple at Senntisten, Azzanadra will tell you that the relic is a catalyst for holy power and is pretty useless by itself. He says that it causes the Barrows icon to give off a larger amount of holy energy, which is then amplified using Frostenhorn to be able to communicate with Zaros. He also says that because the Saradominists have carved their symbol on it that he would want to be far away from Saradominist lands once Zaros sees it.