大蛇の牙 [daija no kiba] or 'big snake's fang' in Japanese.
Final Fantasy XII
Buy: - (sell: 994 gil)
Use: Artemis Bow
Drop: Python
Steal: Midgarsormr
Poach Python
Description: These fangs are thought to ward off evil spirits. Some hang them in doorways to keep misfortune from visiting a household.
Grimoire of the Rift

Buy: - (sell: 300 gil)
Use: Guang Cannon, Hammerhead, Hardedge, Target Bow, Flame Shield
Reward: Cleaning to Loar x2 (repeatable), Green King of Cinquleur x2 (once)
Type: Bone, Rank: ★
Description: This fang is said to have the power to drive off evil. Often hung over doorways.
Final Fantasy Tactics S

Buy: - (sell: 50 gil)
Use: ?
Obtain: Rhode Rum Region/Forest of the Dead
Description: A somewhat uncommon bone
Category: Item