The Golden Armor is a purely defensive piece of equipment: It provides high bonus to its wearer's defensive attributes, as well as complete resistance to Fire, Thunder and Ice when fully upgraded. Its special ability buffs the wielder's Defence when hit by a powerful attack.
Epic Battle Fantasy 4
Found on the Battle Mountain, specifically in the top-right chest on the cloudly screen, accessible after beating the nine-wave foe rush with foes from the Temple of Godcat. Winged Boots are required to get there.