Customizing Weapons
You gain the ability to customize any weapon in your possession automatically once you have reached Guadosalam. To begin customizing a weapon, select "Customize" from the main menu. Any weapon that has an open slot, shown as an empty purple box underneath the weapon when it is selected, can be customized with an ability. Adding an ability requires a specific number of items obtained from enemies These abilities affect certain aspects in battle such as how much damage your character does and the type of damage. Weapons can have up to four empty customization slots and all abilities are active at once, meaning you can create a weapon that has the abilities Overdrive to AP, Triple Overdrive and Triple AP.
Triple Overdrive
In "Final Fantasy X," Overdrive builds when an action is performed, such as attacking an enemy, receiving damage or healing a teammate. Once the Overdrive bar is full, a character can perform an attack that deals high damage to any enemy on the field. The ability Triple Overdrive allows the Overdrive bar to fill three times faster than it usually would. To put this ability on a weapon, you must have 30 of the Winning Formula item. You can gain this item by defeating Ultima Buster in the arena or bribing the Sand Worm enemies.
Overdrive to AP
Ability points, called AP in-game, are awarded at the end of every battle and are used to purchase new abilities and upgrades for your character. The ability Overdrive to AP allows you to gain additional AP any time one of your characters reaches an Overdrive state. To add this ability to a weapon, you must have 10 Door to Tomorrow items in your inventory. These can be stolen from an Ultima Weapon, won by defeating the Bomb King in the arena, or bribed from the Mech Leader or Mech Scouter.
Triple AP
The ability Triple AP allows you to receive triple the amount of ability points when a battle is completed. Combined with both the Overdrive to AP and Triple Overdrive abilities, you can gain a large amount of ability points in a very short time. To add this ability to a weapon, you must have 50 Wings to Discovery. You can gain these by defeating Shinryu in the arena or bribing a Malboro or Great Malboro.