The Priest of Light is a NPC that appears in both Heroes of Mana and Seiken Densetsu 3.
In Heroes of Mana
He governs the holy capital of Wendel. Wielding the Mana Goddess' magic, he offers salvation to the masses with his healing hands. Though not one to use it on the battlefield, his wizardry is impressive and he displayed it in an attempt to defeat Cecelia Baxilios when she attacked Wendel.
In SD3
In the early parts of the storyline the selected main character will head to Wendel and seek out the Priest of Light for advice. That is all main charcters excluding Charlotte as she is the Priest's granddaughter and already in Wendel.