Collect 10 Wisdom Gems. Go to that same island in the bottom left corner in the Southwest sea. The process is basically the same. You talk to the Fairy Princess and choose Wisdom. The Spirit of Wisdom will regain some of its strength. Equip it by going to your "Collection" and choose Spirit of Wisdom. Exit the "Collection" screen. You'll notice that your hearts are surrounded by a blue glow. You will now take less damage from attacks!