A cool idea, but it doesn't really have any point to it as far as game balance is concerned. I mean, the morning star and most of the axes are already underused in comparison to the other great swords as you said before. As far as realism goes, you have a solid argument. Then again, as far as realism goes one shouldn't be able to wiggle a pike through a wall and hit a person on the other side by jumping and wiggling wildly. Plus, unbalanced weapons in general are already slow as all get out.