Aside from the monster featured in many Final Fantasy games, the Behemoth was a creature described in the Bible, in the book of Job. It is the plural of the word "behemah", beast, and, in early Jewish tradition, was believed to be the king of the animals.
ベヒーモスナイフ [behemoth knife] in Japanese.
Final Fantasy III
Stats: ATK 78, ACC 100, AGI +8, weight 0
Use: ONK, THF, NIN
Treasure: Temple of Time
Type: Dagger
Other: was added for the DS version, did not exist in the NES version
A Realm Reborn

Stats: PDMG 37, MDMG 29, ATK 30.6, Delay 2.5, DPS 12.3, DEX +13, VIT +14, Crit rate +17, SkSPD +24
Equip Level: 50, Equip On: ROG, NIN
Item Level: 50, Rarity: Blue
Buy: 5 Behemoth Horn (sell: 250 gil)
Shop: Aelina / Revenant's Toll
Type: Rogue's Arm, Stack: 1, Unique: Yes, Untradeable: Yes, Binding: Yes
Dye: No, FC Crest: No, Materia Slots: No, Convert: No, Desynthesis: No
Glamour: Goldsmithing, Repair: 80 gil / Grade 5, GSM40
Other: as 'Behemoth Knives'
Airborne Brigade

SR+
Type: Dagger, Element: -, Growth: Slow, Cost: 28
Attack: 2,580 (lv1), 11,929 (lv120), 15,678 (lv150), 19,827 (lv180), ? (lv210), 29,190 (lv240)
Defense: 2,550 (lv1), 11,790 (lv120), 15,496 (lv150), 19,596 (lv180), ? (lv210), 28,850 (lv240)
Obtain: ?
SR
Type: Dagger, Element: -, Growth: Slow, Cost: 19
Attack: 1,660 (lv1), 7,667 (lv100), 10,080 (lv125), 12,751 (lv150), 15,657 (lv175), 18,780 (lv200)
Defense: 1,660 (lv1), 7,667 (lv100), 10,080 (lv125), 12,751 (lv150), 15,657 (lv175), 18,780 (lv200)
Obtain: ?
Pictlogica

Stats (lv1): STR +73, SPD +5, LCK +3
Stats (lv25): STR +115, SPD +25, LCK +15
Buy: - (sell: ? gil)
Obtain: event quests Master Challenge R, Master Accela, Master Accela Limited
Type: Dagger, Rarity: ★★★★★, Element: -
Record Keeper

Stats: ATK +64, ACC 95 (lv1), ? (lv5), ? (lv10), ? (lv15), ? (lv20), ? (lv25), ATK +109, ACC 95 (lv30)
Max Level: lv20 (initial), lv25 (first evolve), lv30 (second evolve)
Type: Dagger, Rarity: ★★★★★
Other: enables use of the limit attack Meteorite
Other: unlike most other equipment in FFRK, Behemoth Knife is not from any previous FF but is instead an original equip
Category: Equipment