this is actually just a false rumor that Polpo has spread within Passione to hide the existence of the arrows.So, when the people who took Polpo's entrance test became Stand users,"The Arrow"is an arrow with a mysterious power to turn someone into a Stand user once you stab them with it.Currently, Passione owns 4 of them.They're all managed by Passione's HR Team leader, Polpo.Polpo's Stand, Black Sabbath, is said to have the power to turn non-Stand users into Stand users.However,it was not because of Black Sabbath's power, but the arrow's.