In old times, a hero from the overworld came from the sky and defeated the Master Archfiend Zoma wearing this armor that he found inside the tower of Rubiss. Upon his victory his name, Erdrick became known throughout the land.
Several generations back another hero appears claiming to be the descendant of Erdrick and on his quest to defeat the Dragon Lord he discovered this armor buried under a tree behind a weapon shop in the ruined city of Haukness. After defeating the Dragon Lord, this unknown hero (having now proved his ancestry) also took the name Erdrick and, with the king's daughter Gwaelin, he set out to build his own kingdom.
In more recent years, the descendants of the second Erdrick have spread throughout the world founding three new kingdoms (Midenhall, Cannock, and Moonbrooke) when new evil struck. On the trio's journey to save their land they find the sacred armor while going through the cave to Rhone.