Thief skills are the specil skills that Zidane can use. You can learn these skills from his various dagger weapons that you can find and make throughout the game. The below list gives you some information on the various thief skills.
Name
MP
Description
Learn
Flee
0
Escape from battle with high probability
Dagger, Mage Masher, Zorlin Shape, Ultima Weapon, Germinas Boots
Detect
0
See the enemy’s items
Mage Masher, Orichalcon
What’s That!?
2
Allows back attack
Butterfly Sword
Soul Blade
6
Draws out the hidden power of thief swords
The Ogre
Annoy
4
Inflicts Trouble on the target
Gladius, Sargatanas
Sacrifice
32
Sacrifice yourself to restore HP and MP to the other party members
Exploda, Masamune
Lucky Seven
6
Deals physical damage by luck
Gladius, Exploda, Rune Tooth, The Tower, Thief Hat