The Gerudo Vai Armor set is a fairly unusual armor set in that it’s one of the few that can’t be upgraded at the Great Fairy Fountains and overall, it has very little use outside of the quest to gain entry to the Gerudo city. The Gerudo Vai armor set is aimed to disguise the wearer to look like a woman, allowing Link to gain access to the Forbidden city in the Forbidden City Entry Main Quest.
Each piece of this armor set will provide 1 Armor, but wearing the full set will grant you heat resistance, which is an important part in being able to find the Gerudo city in the first place. The desert will damage Link in the same way the snow does. Wearing this full armor set will grant Link resistance to the heat of the desert.
Where to find the Gerudo Vai Armor Set?
As previously mentioned this is required for a quest and part of this quest will guide you to the point of needing it. Once you get to the main Gerudo town, not the oasis, there will be a shrine. Next to the shrine is a man called Benja. This is where you can kick off the quest to get the armor.
Head back to the Bazar after getting the quest and go up onto the roof of the main building there, there is a ladder around the back. A woman (its a DUDE) will be there. Chat to him and give compliments, he will reveal the secret and sell you the clothes for 600 Rupees