Grenade Bomb is Barret's first level 2 Limit in Final Fantasy VII. It performs a physical attack that will either hit a single target for 3.375 times Barret's normal physical damage, or hit all targets for less. Using it eight times unlocks Hammer Blow.
The Grenade Bomb attack consists of Barret firing a grenade at its target. The grenade is not visible, though after it connects, it causes an explosion hitting adjacent targets.
Grenade Bomb is obtained by killing 80 enemies with Barret. This can be sped up using the Enemy Skill Materia, particular if Matra Magic has been learned. Barret will need to equip this and can use Matra Magic to quickly kill enemies in the Grasslands Area, in the Mythril Mine, or in the forests of the Junon Area. Later on, the large forest in the Nibel Area past Mt. Nibel features a wave of six enemies (Battery Cap) and overall has around 4.4 enemies per encounter.
Grenade Bomb deals 3.375 times Barret's normal physical damage if fired against a single enemy. If fired against a group, it deals slightly less damage, distributed among the enemies. It is a versatile attack that can reliably hit multiple enemies, while still remaining useful against single targets and bosses. Grenade Bomb's damage is based on Barret's Strength stat and his currently equipped weapon.
After using Grenade Bomb eight times, Barret will learn Hammer Blow, which will perform Instant Death on an enemy that is not immune to it. Once obtained, Hammer Blow is best against all single enemies aside from bosses, as most normal enemies are not immune to Instant Death until later. However, Grenade Bomb is still better against waves of enemies, and is the only option on bosses and enemies immune to Instant Death.
Grenade Bomb is outclassed by Barret's level 3 Limit Breaks. Against multiple targets, Satellite Beam deals a consistent 2.1875 times Barret's normal damage to all enemies, while against single targets, Angermax causes 18 hits of half damage each. This means that Grenade Bomb can be replaced once Barret's level 3 Limit Break is obtained.