Defeat the indicated character under all difficulty settings to earn the corresponding crystal.

Crystal	How to unlock
Testament to Acumen	Defeat Shantotto.
Testament to Allegiance	Defeat Cloud.
Testament to Conviction	Defeat Tidus.
Testament to Heroism	Defeat Warrior of Light.
Testament to Impudence	Defeat Vaan.
Testament to Knavery	Defeat Zidane.
Testament to Knighthood	Defeat Cecil.
Testament to Leoninity	Defeat Squall.
Testament to Mulebrity	Defeat Terra.
Testament to Rectitude	Defeat Firion.
Testament to Refulgence	Defeat Lightning.
Testament to Wanderlust	Defeat Bartz.
Testament to Youth	Defeat Onion Knight.