Here's another idea linked to the alternative magic sword I mentioned before. I know some people have bandied about the idea of scaling a magic sword with the character, so that a player doesn't ditch a +1 sword because they found something better. This is real easy to do in a descending AC system, using the same basic idea from the previous post: the magic sword treats all mundane armor as having an AC no better than the character's level.
Thus, a magic sword found by a 1st or 2nd level character is no different in combat than an ordinary sword, although it will resist or be immune to damage and can hit creatures immune to non-magic weapons. But as level increases, the defender's AC is capped, until at 9th level, a lord with a magic sword treats all opponents as if they were unarmored.
Again, I'm not sure I would use this personally, especially since I don't like the idea of magic weapons that scale. But there it is, for anyone who's interested.