Drop rates have been raised to make the game less challenging for months of farming, and increase ruby purchases. Expect a lot of fruitless farming.

Wind Dragon Armor is a set of four items which can be unobtain by attacking Savannas level 7 and higher with a Great or Elemental Dragon as part of the attack. Alternatively, they can be purchased from the shop. Once you have obtained all four pieces, and have Outpost 4's Dragon's Keep at level 8+ you will be able to include the Wind Dragon in your attacks.

As the items have a little chance of being found on each attack, many attacks will likely be necessary to find the set. Researching Aerial Combat, upgrading to higher level Dragon's Keeps and unlocking other Elemental Dragons will reduce the minimum time between attacks.
340px-Armadura Dragon Viento

Wind Dragon Armor