カイザーナックル [kaiser knuckle] in Japanese.
Final Fantasy III

Stats: ATK 50, ACC 100, weight 0
Use: ONK, MNK, BLB
Treasure: Amur Sewers
Type: H2H
Final Fantasy V
Stats: DEF 8, MDEF 1, STR +5, weight +1
Equip: all
Buy: - (sell: 7,500 gil)
Drop: Iron Fist / Pyramid
Treasure: Great Sea Trench
Final Fantasy VI
Stats: ATK 83, Holy element
Equip: Sabin
Obtain: ?
Description: Set of spiked knuckles imbued with holy might
Final Fantasy VII

Stats: ATK 44, Hit 110%, MAG +13, Critical +1%
Slots: 2+1+1+1+1+1+1, Growth: Normal
Equip: Tifa Lockhart
Buy: 15,000 gil (Sell: ?)
Shop: Junon
Treasure: Whirlwind Maze
Other: cannot be used with Throw
Final Fantasy IX

Stats: ATK 75, Wind element
Equip: Amarant
Abilities: Counter, Countdown, Curse
Buy: 18,000 gil (sell: 9,000 gil)
Shop: Daguerreo (weapon shop (disc 4))
Steal: Silver Dragon
Obtain: dig up on the world map with the Chocograph 'Dusk Plains'
Description: Claws with a wind spirit dwelling inside
Type: H2H
Other: inflicts Trouble with 15% probability with Add Status active
Final Fantasy XIII-2
Kaiser Knuckles
Slot cost: 75
Ability: Strength +40, Chain Bonus Lv 1, ATB Rate +5%, Accessory Ability Group: -
Buy: - (sell: 6,000 gil)
Treasure: Academia (400 AF)
Drop: Proto-behemoth (5%)
Description: ?
Durable Kaiser Knuckles
Slot cost: 100
Ability: Strength +60, Chain Bonus Lv 1, ATB Rate +8%, Accessory Ability Group: -
Buy: 18,000 gil, Kaiser Knuckles, Sinister Fang x5 (sell: 9,000 gil)
Description: ?
Crystal Chronicles
Stats: STR +1
Treasure: Tida, cycle 1
Other: an Artifact
Airborne Brigade

SR+
Type: Fist, Element: Wind, Growth: Normal, Cost: 21
Attack: 1,790 (lv1), 7,202 (lv120), 8,566 (lv150), 9,931 (lv180), 11,295 (lv210), 12,660 (lv240)
Defense: 1,840 (lv1), 7,401 (lv120), 8,803 (lv150), 10,205 (lv180), 11,607 (lv210), 13,010 (lv240)
Obtain: any chest that gives this rank
SR
Type: Fist, Element: Wind, Growth: Normal, Cost: 17
Attack: 1,420 (lv1), 5,708 (lv100), 6,791 (lv125), 7,874 (lv150), 8,957 (lv175), 10,040 lv200)
Defense: 1,410(lv1), 5,668 (lv100), 6,743 (lv125), 7,819 (lv150), 8,894 (lv175), 9,970 lv200)
Obtain: any chest that gives this rank
All the Bravest
Stats: ATK +7, Number: P21, From: FF3
Equip: Monk, Tifa, Red XIII, Snow Villiers, Chocobo
Drop: Ghast
Description: These knuckles underline the undeniable beauty in beating the life out of something.
Record Keeper

Kaiser Knuckles (V)
Stats: ATK +82, ACC 95 (lv1), ? (lv5), ? (lv10), ? (lv15), ? (lv20), ? (lv25), ATK +131, ACC 95 (lv30)
Max Level: lv20 (initial), lv25 (first evolve), lv30 (second evolve)
Type: H2H, Rarity: ★★★★★
Other: enables use of the Tenacity Soul Break when equipped by Galuf

Kaiser Knuckles (VI)
Stats: ATK +75, ACC 95 (lv1), ? (lv5), ? (lv10), ? (lv15), ? (lv20), ? (lv25), ATK +124, ACC 95 (lv30)
Max Level: lv20 (initial), lv25 (first evolve), lv30 (second evolve)
Type: H2H, Rarity: ★★★★★
Other: enables use of the limit break Rising Phoenix when equipped by Sabin

Kaiser Knuckles (XIII)
Stats: ATK +66, ACC 95 (lv1), ? (lv5), ? (lv10), ? (lv15), ? (lv20), ? (lv25), ATK +110, ACC 95 (lv30)
Max Level: lv20 (initial), lv25 (first evolve), lv30 (second evolve)
Type: H2H, Rarity: ★★★★★
Category: Equipment