There are two Japanese-language abilities that are both translated as Treasure Hunter. The first is トレジャーハンター [treasure hunter] in Japanese. The second is アイテム発見移動 [item hakken idou] or 'item find movement'.
Final Fantasy XI
Type: Job Trait
Description: Increases chance of getting treasure
Other: works as a debuff (must hit at least once, is removed if aggro is lost and the mob returns to its place), when used as THF main Treasure Hunter can upgrade effectiveness multiple times (a single-digit-or-less percentage chance of it happening after initial application). THF main can get a maximum of +8 Treasure Hunter (up to +12 through procs), THF sub can only get +4
Other: affected by various equipment
Other: the Blue Magic spells that give trait points for this ability are Charged Whisker (6), Everyone's Grudge (6) and Amorphic Strikes (6)
Other: トレジャーハンター in Japanese
Treasure Hunter I
Learn at: THF15, BLU98+
Other: to get this ability on BLU, set all three appropriate Blue Magic spells
Treasure Hunter II
Learn at: THF45
Treasure Hunter III
Learn at: THF90
Final Fantasy Tactics
Type: Movement Ability
Learn: Chemist (100 JP)
Effect: Allows you to find any hidden items on any tile you're standing in. Chances of finding a rare item increases with low BRV
Other: アイテム発見移動 in Japanese
Category: Ability