Following the Steel post, I have had a few thoughts.
For those not aware, I run AD&D. The suggestions below apply to that edition.
Faced with the task of comparing materials used to create weapons (and armor), the first task as I see it is to define when contact occurs. It isn't enough to simply say this misses or hits ... a "miss" can still hit the defender's weapon or armor, or may miss entirely due to dexterity.
Consider - what is the difference between attacking an unarmed opponent (who can't parry), or an opponent without a weapon but with armor? And when does a "hit" cause damage through armor, as opposed to around it? Being hit on your chest plate with a mace hurts ... and it can damage the body and break the mace at the same time.
In trying to define when these things happen, I have constructed the following table:
What I am attempting to convey is the idea that strikes that "miss" an opponent do not miss the majority of the time due to the wielder being unable to make contact. In a one minute round (or 12 seconds in my world), there's going to be plenty of contact in that period ... therefore, the attacker's weapon is going to strike the defender's weapon, armor or body - according to the above table, 95% of the time. The other 5% indicates that the attacker has dropped ... and inherent in the table (though not specified) is an additional 5-20% chance of pure missing due to the defender having dexterity.
A drop, too, would indicate that the weapon struck something - that being the floor. My rules on dropping can be read here. I don't feel I need to extend them at present.
The exact ranges above are doubtlessly going to be a point of contention. So far, I haven't had any chance to test anything of the above - so for the moment we'll call it Hegel's abstract begging for antithesis in pursuit of the concrete.
In the column "Defending Weapon," the attack (discounting a roll of '1,' which I shall not reference again) either hits the body or hits the defender's weapon. If it hits the body, damage is done and the attacker's weapon is unaffected. If it hits the defender's weapon, however, both weapons ought to make some kind of roll, possibly resulting in either or both being broken or not. The balance could be adjusted by the effect of a hard weapon (steel) vs. a soft weapon (bronze). Furthermore, either weapon may NOT break, but may be blunted ... which would mean the weapon continued to function as a weapon, but that it did perhaps a point of damage less, or the user was more likely to miss.
I have made no rules for this. I am merely stipulating at which times said undeveloped rules would apply.
Now, as it happens, I am proposing that whenever the d20 rolled an "8," regardless of the level of the attacker, the two combatant's weapons would come into contact and their sturdiness would be challenged. However, if it happened that a 3rd level fighter rolled an 8 against an unarmed opponent, we all know that would "Hit" and the fighter would cause damage. For the remainder of this post, please consider the possibility that the hit would occur, and would do damage, but that it was damage done against the weapon arm/body of the defender. In other words, yes, I hit your sword; the contact sent a shock down your arm and the shock did damage. I hit your sword because I rolled an 8. I did damage because my level hit the equivalent of your armor class.
I hope that's clear.
As such, no matter what the opponent's armor class is, if they are unarmored, and you roll anything between a 2 and a 9, you hit their weapon and not their body - and physics does the damage.
In the column "Padded," it must be noted the defending armor overlaps the defending weapon, whenever a 7, 8 or 9 is rolled on a d20. It is assumed that IF the defender has a weapon, then a roll of 7, 8 or 9 hits that weapon; and if the opponent does not have a weapon, then a roll of 7, 8, 9 or 10 hits the defender's armor. The armor, then, is more beneficial if you've lost your weapon; with your weapon, it only improves your resistance to damage by 5% ... which is in keeping with the spirit of the pre-existing combat system.
Now, it should also be noted that the existence of a shield is a special condition. On the table I am proposing that, like the armor, the defender's weapon will block hits between 2 and 6 ... and that if the defender does not possess a weapon, but has a shield, the shield will block hits between 2 and 6. HOWEVER, if the opponent does not have a shield, and does not have a weapon, a die roll of 2 to 6 on a d20 will hit the defender's body and cause damage!
This is not in keeping with the pre-existing combat system.
Nevertheless, it does address something the combat system never addressed - how does the lack of a weapon or sword improve the attacker's chance to hit? It ought to, after all ... but without vastly reworking the entire convenient system as designed, how is that accounted for?
Well, as I suggest above. I think its a fairly good idea, myself. Why does it matter that a low die roll hits as opposed to a high one, if you change the situation? A percentage is a percentage, right?
If the defender has a shield, then the weapon and the shield must both roll for breaking or destruction. And this brings up a salient point. If an 10 is rolled, which hits the padded armor as stipulated above, that TOO should affect either the armor or the weapon. While padded armor seems unlikely to break a weapon, there may be other considerations (getting the weapon somehow hooked or caught by the armor) - and certainly the armor is not indestructible.
So for the remainder of columns, in each case the armor covers more of the range of possible rolls (without changing the existing system's specifications regarding damage). The greater the armor, the more likely it is that the attacker will hit it - so that it will have to roll again and again in order to endure. The armor may take constant pounding on the center of the breastplate - but how long can a clasp, a rivet or a joint hold before it breaks and reduces the armor one degree in defense? These too are rules I haven't written - but it seems to me the above table explains when they would apply.
The shield, when it does defend regardless of the weapon, is considered as according to the pre-existing system to lay overtop the armor - so that if the defender is in plate, the shield is hit on an 18, if the defender is in ring mail, the shield is hit on a 14, and so on. The reason why it is done this way, rather than to presume the shield is always hit on a 10, is that the system must be flexible to allow for when the defender does not have a shield. Exactly as in the game, if the defender is in ring without a shield, the 14 hits the defender's body.
Obviously, dexterity is stacked on top of the shield, reducing hits to the body that are rolled above 9. What this means from the above is that if the defender had plate and shield, and a 16 dexterity, and possessed a weapon, then no attack would EVER hit the defender's body. But the reader will please note, as I have explained above, it is not necessary to hit the body in order to cause damage. A bent piece of shield, a bent weapon or the rent pieces of the armor itself, driven into the defender's body with your mace, will kill quite effectively without your mace ever actually touching flesh.
It's just a matter of the way you look at the problem.