Equipment Farming is a technique used to gain equipment from enemies that carry them.
This method is done by fighting the particular enemy carrying your desired item over, and over and over, until they drop it. They will be more likely to drop it if your character has a higher Luck stat, which can be increased by equipping certain accessories.
Thief's Gloves and Thief's Hat will each increase an item's drop chance by 1.2x. You can gain the Thief gear by fighting against two variations of Zidane in Quick Battle.
Equip the set Allure of Honey to raise the Drop rate x 1.5, buy from the PP Catalog the Item Drop Rate Up (One Fight or 10 Pack), be on your Special Day, all this boost your chances.
The Dangerous Fortune (US: Dangerously Lucky), Moogle Charm (US: Mog's Amulet), Fake Mustache and Rabbit's Foot accesories combined with the Super Ribbon (To stop the Charm/Amulet breaking) and the aforementioned Thief's Gloves make for an effective build for equipment farming. Equipping Incense of Miraclein (US: Mystery Incense) and Aromatic Tree of Miraclein (US: Mystery Resin) plus any LUK+4 Trade items like Rosetta Stones or the Lores to further boost the character's Luck is also a viable option