A kunai was a Japanese tool for masons, cheaply and plentifully produced. The tip was used to dig holes and pry, while edges were for crushing plaster and wood, and as such were unsharpened. The kunai also had the advantage of being a crude (and cheap) sort of weapon if you only sharpened it, being a good thrusting and stabbing weapon in that function. Most kunai are around 40 cm long, with the common range being 20-60 cm.
くない / 苦無 [kunai] in Japanese.
Final Fantasy IV
Stats: ATK 35, ACC 100, SPD +1
Equip: Edge
Buy: 4,000 gil (sell: 2,000 gil)
Shop: Eblan Cave
Treasure: Tower of Babil B4
Obtain: starting weapon on Edge
Final Fantasy V
Stats: ATK +26, AGI +1
Equip: Ninja
Buy: 600 gil (sell: 300 gil)
Shop: Karnak, Lix
Other: can be used with Spellblade
Final Fantasy VI
Stats: ATK 82
Equip: Shadow
Obtain: ?
Description: Basic, straight-bladed ninja dagger
Other: Can be used with Two-handed
Final Fantasy Tactics
Stats: ATK 9, Parry 5% (when available)
Range: horizontal 1, vertical up 2, vertical down 3
Equip (job): Ninja, Onion Knight
Equip (character): Sword Saint
Equip (enemy): level 13
Buy: 5,000 (sell: 2,500 gil)
Shop: (available after Alma joins in ch3) Trade cities
Description: A multipurpose sword for ninjas.
Other: can be used with Dual Wield, Doublehand and Throw
Record Keeper

Kunai (IV)
Stats: ATK +5, ACC 83 (lv1), ? (lv3), ? (lv5), ATK +21, ACC 83 (lv10)
Max Level: lv3 (initial), lv5 (first evolving), lv10 (second evolving)
Type: Dagger, Rarity: ★
Category: Equipment