A Cupid's Bow refers to a sigil inscribed on a cupid's palm. It appears as a tattoo in the form of a bow and an arrow. This sigil enables cupids to catalyze emotions and relationships among humans. The sigil is revealed upon the will of the cupid. Removing this bow, or the image of the bow, is the second ingredient for the spell to expel angels from Heaven. This was achieved by Castiel when he carved out the bow from a cupid who willingly gave it up.