Grenade Launcher

It eats rockets and spits out grenades that arc hard on the way. They go off on contact with an enemy or when the fuse burns out, and they do not care whose side you are on. A grenade that lands at your feet will hurt you. Aim high at any real distance, and think twice before firing it down a narrow tunnel.

You get this one far earlier and it hits harder per shell, but the arc and the fuse mean shots land late and land where the floor is rather than where you pointed. The Rocket Launcher trades that away for flat shots, instant detonation and a large bonus for connecting directly. Against something fast, the direct hit wins outright. Against a slow, large target or a packed crowd, being able to lob explosives over cover is worth the delay.

Take raw damage for fighting. If you are mostly using it to dig or to spray liquid rockets around, more shots per second is worth more than more damage per shell.