Grenade Launcher CLUSTER
From Halopedia, the Halo wiki
The Grenade Launcher CLUSTER is an unused weapon in Halo 5: Guardians. The gun can be found within Halo 5: Forge, and appears to have been fully modeled, textured, and functional. It is unknown why it was cut from the game.
Like other M319 grenade launchers, it can be fired immediately or held down to manually detonate on release. Additionally, manual detonation results in an EMP effect. Upon detonation, the projectile will split into 8 separate projectiles dealing damage in an area. Due to the spread and EMP effect, the secondary fire could be useful in disabling air vehicles.