Instructions
At the start of the game, register Zack at the mission board in the Shinra building. Once this is done you can enter any save point then open the main menu and access the "Missions" sub menu. This displays a list of all available missions.
Play the game until you reach level nine, the "Great Cavern Of Wonders." Complete all the sub missions until you have access to the sixth chapter, "Doors To The Unknown."
Complete all the "Doors To The Unknown" sub missions until you have access to the sixth mission titled, "The Reigning Deity." The objective of this mission is to slay the boss "Minerva" and your reward will be the "Divine Slayer" accessory.
Perform a "Steal" attack when the battle against Minerva starts to instantly get 99 "Phoenix Downs." If you have the item called "Brigands Gloves" equipped (and you should if you have done all the extra missions up to this point) then the steal move has no chance of failing. Minerva will kill your character but you will restart at the save spot with the Phoenix Downs still in your possession.
Go to the nearest shop and sell the Phoenix Downs for cash. Repeat the process of stealing from Minerva then selling at the shop to build up your cash reserves. Use the cash to buy the best equipment for your character.
Use the "Gill Toss" move against Minerva in battle. This move damages enemies at the cost of some of your money. Since you have already built up a lot of cash, you will be able to do some major damage. After you defeat her, the "Divine Slayer" is yours.