Many would say that for a mouse the choice of using a massive sword is a bad idea. And that'd be true if this particular mouse wasn't host for a demon king. While it is a constant inner struggle there are benefits to staying in control. Enhanced strength is one of them. This allows him to move that sword surprisingly well, to him its as light as a feather. Such a larger sword makes it easy to dispose of the demons that constantly pursue him, as almost have of the ability to heal themselves in seconds, the best solution is to cause massive amounts of damage instantaneously. A sword this size makes it easy to take care of multiply enemies at once and even be used as a shield, in short they don't know who they are messing with.
