Josh Calloway has a weapon called a “Legacy.” This weapon can take many forms, but he starts off with just two; a Sword and Rod. As he progresses through the game, he battles various bosses who have their own legacy weapons. Defeating these bosses rewards Josh with their weapon. This means that he has the ability to switch to that weapon, even in the middle of a fight, allowing you to string large combos together.
Contained inside Josh's “Legacy” is the transformed soul of Josh’s girlfriend. According to the Wisdom Corporation (who created the weapon, and also act as the big evil corporation that Josh is aiming to bring down) this is supposedly what gives the weapon it’s power, by fusing a human soul with a rare sort of metal found only in the lost city of Atlantis.