Well, it is an item that provides a bonus to the PC's skill, so I always imagined superior and magic swords as being lighter, stronger, more flexible with a great edge (for superior swords) or a near unbreakable edge (for magic swords, i.e. never dull), while blunt weapons are harder and lighter, yet having the (magically provided) property of hitting as if they had more mass.
A magic sword is as superior in craft as modern composites are to the steel the Titanic was built from. Being almost unbreakable, their ability to penetrate armor would be far superior to mundane weapons, something the bonus simulates, yet fails to express superiority over mundane/superior weapons with the same bonus, i.e. two +10 swords, one magical, one superior, offer the same increased chance to score a better hit in melee. Perhaps the answer is to remove bonuses from superior gear, or assign magic weapons armor slaying ability.
lynn