The Golden Fleece is an item that is based on the Golden Fleece of Greek mythology which is of unimaginable value.
The Golden Fleece had a bug in its code that allowed a player to use its flight without holding it. The glitch was caused by equipping the Golden Fleece and another gear at the same time by pressing both keys at once. This was used by many players who had this gear during the timespan in which it was possible; to be an effectively invulnerable target since that can fly and use any gear in tandem with flight.
Attempting this glitch currently will result in your character flopping around harmlessly onto the ground.