From Final Fantasy Wiki

An Augment as it appears before it is acquired by the player.

The Augment Ability system (デカントアビリティシステム, Dekanto Abiriti Shisutemu) is a support ability system from Final Fantasy IV on the Nintendo DS. It allows each character to equip abilities that have several different effects, such as Counter, although some do add new commands, such as the Sing or Twincast command.

A character can have as many Augments as they want, but they can only equip four augment abilities at once, as the Items ability cannot be removed.

An Augment Ability is received as a Key Item. For a character to learn the ability, the item must simply be used on them. However, once the item is used, it can't be used again. As well, as noted before there are situations below where multiple augments can be received from the same person. If the player fulfills the requirements to receive multiple augments, they will receive all of them. For example, if the player gives Edward one augment, he will give them Bardsong and Salve, rather than just Bardsong.

It should also be noted it is impossible to receive all augments in a single playthrough. The simple reason for this is that there are not enough to go around early in the game. In order to receive all of his augments, Edward must be given two augments, and the only augments accessible while he is in the party are Auto-Potion and Item Lore. However, this means that, when Palom and Porom leave the party, the player will only have the Curse and Counter augments, and getting all of their augments requires the player to give Palom and Porom three augments total.

Simply put, the player cannot give Edward two augments and have enough left over to give three to Palom and Porom. Thus, the player must ultimately give up either the Hide or Dualcast augment, as both cannot be acquired due to the above information.

Ability List