You could always give a weapon that is in someones possesion a FORT save vs. massive damage, and only then be destroyed. If it succeeds, it is only damaged, say -2 to hit & dmg., until it is repaired. A 10 check for normal or MW items, a 20 if magical, but no other special requirements since it was not permanently damaged. Just don't count the HP done as "damage".
For those who think a Sunder will miss to often, there are many ways to get bonuses to hit that will work. True Strike, obviously, your own magic weapon, the Strenght domain would be great at this point for a bouble whammy. Not to mention that the weapon may be easier to hit than the foe. It's not Mage Armored, nor would it have cover bonuses, since it has to be out in the open to hit you.