This seems an appropriate addition to my AC discussion above.
I recently bought Unearthed Arcana, and amongst the variant rules within I found one relating AC and damage resistance.
In similar (but fewer) words than myself they pointed out that there is a common mistake whereby people forget that beating AC means bypassing the armour to do damage, not just to hit the opponent.
However they go on to suggest a horrible bastardised version of the DR and AC rules. They do this for balance reasons, so the game mechanics remain functional, but in real-world terms it makes even less sense.
Basically the suggested system is this:
AC for different types of armour is significantly reduced, and then a damage reduction is applied on top.
So, in other words, you bypass the armour with your attack (by beating the AC) you then have the amount of damage you do reduced by the armour.
It seems to contradict itself, doesn't it? You're both bypassing the armour, and having it obstruct your blow. Hm...
This makes even *less* sense when you consider the different types of armour.
So say you stand with your rapier facing an adversary in full plate armour, and you skillfully score a wound by slipping the blade between the plates of steel (as rapiers were initially designed to do).
Now consider your tactics against someone in chainmail... you would as before try to score a hit in the regions where the armour doesn't cover.
So then, why would such a wound on the plate mail opponent be less damaging than the wound on the chainmail-wearer?
It really does take a good system and twist it into an absract and counter-intuitive concept for the sake of balance...

