Man, this may seem kind of out there, but I'd actually argue that you go ahead and implement the weapon v. armor type rules.  I feel weird advocating them, because they're more or less the opposite of how I like games to be constructed, but stay with me.  First, they're not nearly as bad as they look at first.  Secondly, they're pretty vital to the functioning and balance of the combat system.  If you look at what they do, they're there to make the different weapons a little more balanced in some respects.  You have weapons that do a lot of damage, or that are very fast, and you have weapons that are good at cutting through heavy armor.  That's the reason they exist - so that there's some conceivable reason to use a weapon other than a sword, essentially.  You actually open up way more space for characters to be differentiated if you implement them.<br/><br/>This was a non-issue in OD&D, because all weapons did 1d6.