How to upgrade armor in Zelda: Breath of the WildĮach Great Fairy Fountain you unlock allows you to upgrade a piece of armor by one star. Once unlocked the Great Fairies at the fountains will offer armor upgrading services. The first fountain will cost a paltry 100 rupees, the second will be a more significant 500 rupees, the third fountain opened will cost you 1,000 rupees, and the fourth is a whopping 10,000 rupees. The fee to unlock the fountains goes up with each one you unlock.
Once you find a Great Fairy Fountain, the locations of which you can find below, you'll need to pay a certain amount of rupees before the Great Fairy within will assist you.