Hero's Charm

The Hero's Charm is a Mask in The Wind Waker that enables the player to see the life energy for enemies when equipped. It is worn on the face, and the life energy appears as a red bar next to the enemy when it is L-Targeted. It is obtained after giving Miss Marie 40 Joy Pendants.

In Boss Battles, the energy is displayed at the bottom of the screen. But Ganondorf for some reason is not.

Also, the two eyes on the mask are the sheikah eye symbols