While direct energy weapons are fairly common in this universe; most handheld weapons still involve throwing soild objects at targets to make holes in them. This bullpup configuration use electro-thermal breech system in which liquid in the cartridge is converted into plasma to propel the cartridge out of the weapon. It is aystem that has actual been tested in the real world, and produces a much higher velocity than solid powder. Theoretically you just water to produce to the plasma and if necessary systems can switched back to fire conventional powder again.
The grenade launcher can fire both unguided and smart munitions that can be guided by FOs, UCAVs or AFV in the area.