Concentrate

Concentrate, also known as Concentration, is a support ability that generally makes attacks more likely to hit.

Final Fantasy IX
Concentrate can be learned by Eiko and Dagger and it increases the effectiveness of White Magic spells by 50%. It is learned from the Robe of Lords and Rosetta Ring, and 10 Magic Stones are needed to equip it. Mastering this ability requires 80 AP for Garnet and 90 AP for Eiko.

Final Fantasy XIII
Unlike previous installments in the series, Concentrate is not an ability accessible to players. Rather, it is a very powerful attack used exclusively by the Undying Cie'th, Attacus against a single target. Once chosen, he will rush up to his target and charge his attack while removing all debuffs from himself and placing Deprotect and Deshell on his victim before striking. It is an extremely devastating attack and can easily take away over 15.000 HP, if not, KO the victim if they are not in the Sentinel role when the attack strikes.

Final Fantasy Tactics
Concentration is a support ability the Archer learns that allows the character to ignore a target's Evasion. It costs 400 JP to learn.

Final Fantasy Tactics Advance
Concentrate is a support ability that increases Accuracy by 50. It is found in the Archer and Gunner classes. It requires 300 AP to master and is taught by the Target Bow (Archer) and Longbarrel (Gunner). It is considered to be overpowered because it allows use of skills previously balanced by poor Accuracy with significantly higher rates of success.

Final Fantasy Tactics A2: Grimoire of the Rift
Concentrate, while returning in the sequel, has less useful utilities. The ability is only accessed by weapons obtained later in the game, and the Accuracy boost is minimal at best, leaving low Accuracy attacks still inaccurate. It is learned by the Archer class for 250 AP from the Target Bow and by the Fusilier for 250 AP from the Longbarrel.

Dissidia Final Fantasy / Dissidia 012 Final Fantasy
Concentration is a support ability learned at Level 71 in Dissidia, and Level 58 in Dissidia 012. It increases the character's Bravery by 10% of their level's base Bravery approximately every one and a half seconds if the character takes no action for five seconds. Mastering Concentration learns Concentration+, which grants +30% Bravery, then Concentration++, which grants +50%. Taking any action or being attacked ends Concentration's effect.