Concentrate

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

Final Fantasy IX
Concentrate can only be learned by Eiko Carol and Garnet. It increases the effectiveness of curative spells by 50%.

Final Fantasy Tactics
Concentration is a support ability the Archer job 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. It is found in the Archer and Gunner classes. 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
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.