Brad has based his writing within the framework of the Traveller SF RPG. In that scope weapons range from swords right up to man portable fusion guns, depending on what tech level the planet an adventure is set on.
I run a Traveller campaign even today and the players characters are mostly armed with gauss pistols and advanced combat rifles. Energy weapons exist, but are expensive and often quite illegal.
A slug throwing weapon is still the best way to stop an opponent. That might mean gauss, gravitic or chemical.