I've often considered applying the "for every action, there is an equal and opposite reaction" law of physics to these kinds of attacks. For every point of damage the attack does to the wall, have the wall do that much damage back to the weapon, before applying hardness in both cases. If the wall's attack would break the weapon at a lower damage level than the weapon breaking the wall, then that's what happens.
Norfleet said:I think we can rule that an axe is considered to be an inappropriate weapon for lopping through stone walls, as per the "inappropriate weapon" rule, because the vision of a barbarian chopping down the Empire State Building with an axe is just too silly.