I haven't got BRP zero to hand, and this is off the cuff, but how about
:
1) Attack vs. Dodge is an Opposed Roll per the opposed skills rule (with a bit of fine tuning and clarification#).
2) Attack vs. Parry is
not treated as an Opposed Roll
i) A successful (critical, special or normal) parry blocks the parrying objects AP from a succesful (critical, special or normal) Attack's damage roll.
ii) Whichever "object" achieved the lesser degree of success out of the attack or parry reduces its AP by 1 if its AP were exceeded by the other objects damage, plus an additional one for each degree of success less.
iii)Where sensible (e.g. Impaling weapons vs. Shields) aspects of weapon special effects may (GM's discretion be applied) e.g. impaling weapons getting stuck in a shield.
So... Parrying with a shield, even perfectly, probably won't break a sword, and may well not stop all the damage, but unlike armour CAN'T be by passed (and the shield will have a LOT of AP); weapon AP's have a role, and weapons and shields do degrade, but slowly.
And in the past in RQIII I've let characters use their weapon skills as a Maintenace roll with appropriate resource's to hand to "first aid" their weapons and shield and replace lost AP, so I'd certainly allow that as a possibility.
Quite like that actually, will have to try it some time...
Cheers,
Nick Middleton
# Specifically, that when Degrees of Success are tied, the higher roll wins but is in ALL cases treated as having only achieved a normal success, so ties on any DoS result in a normal success for the winner.