Protect - Reduces damage multiplier of incoming physical attacks by half.

Protect [!White] - Always Hits.

Red Mage | White Mage

Buyable at Carwen, Karnak, Jachol for 280 gil

Black Mage | Blue Mage | Freelancer | Mime | Red Mage | Summoner | Time Mage

World 3, Wonder Rod

Mighty Guard [!Blue] - Always Hits. Also gives Float and Shell.

Blue Mage

World 3, Overworld (Sea, G3 on this map) - Stingray (Must be Confused/Controlled)
The Rift, Dimensional Castle (Boss) - Azulmagia (Must be Reflected)
The Rift, The Void (Boss) - Shinryu (Must be Reflected)

Beastmaster

The Rift, The Void - Crystelle

Dragon Defense [!Mix] - Always Hits. Also inflicts Reflect, Regen, and Shell.

Chemist

Mix Phoenix Down + Dragon Fang

Protect Potion [!Mix] - Always Hits. Also inflicts Shell.

Chemist

Mix Turtle Shell + Turtle Shell

Iron Draft [!Drink] - Always Hits.

Chemist

World 2, Buyable at Regole, Bal Castle, Quelb, Surgate, Moore for 110 gil
World 3, Buyable at Mirage for 110 gil

Defender [Weapon] - Use as item.

Freelancer | Knight

World 3, Overworld (Various Sea Areas, best directly west of Istory Falls) - Sea Devil (Rare Steal)
World 3, Overworld (Phoenix Tower area) - Landcrawler (Rare Steal)
World 3, Fork Tower