This idea is based off a weapon you can install on your mech in the Java game: Steel Sentinels.
Basically it feels like a frag grenade launcher.
So what exactly does this thing do?
It shoots a fire bomb, that will explode in the air in multiple shrapnel pieces.

(Fire bomb just launched, same projectile as after the explosion)

(Fire bomb exploded in the air.
So, what i would like to see in a nutshell:
A weapon that shoots a gravity rocket type of rocket that will explode in the air into multiple shrapnel pieces.
If the rocket hits an enemy, it will only deal a small amount of damage and will not result into shrapnel explosion.