The gunblade was a real weapon in history, except it wasn't a pistol. A gunblade or Gunsword was simply a rifle what had a full length sword blade slung underneath it. The blade would be almost purely for slicing and it's reasoning was simple: Reloading a weapon of the musket style was something very difficult to do under pressure, you needed time to be precise and you were defenceless when doing so. Therefore soldiers often carried swords with them or long knives for melee combat. The gun blade was an innovative idea of combining the sword and the gun so that the soldiers required less kit. However it was a deeply flawed system. The weapons would be heavy, very heavy in fact almost unweildly heavy this affected aim and also it's use as a melee weapon. It was replaced shortly afterwards with a new invention in the form of the bayonet. The bayonet combining the lightweight blade of a dagger with the length of the rifle allowing it to act as a spear like weapon when attached or as a dagger when not attached.