The Sigil said:[B3.) **Great** for breaking items and sundering stuff since Sonic energy does *full damage* to objects. With a +1 sonic rapier, you're dealing (on average) 8 points of damage - not quite enough to overcome hardness unless you have a strength bonus, but it also means that you have a good shot of getting by hardness and doing some sundering. Much better than the 5.5 average points the +2 rapier provides. Someone with a +3 Str bonus will, on average, damage his opponent's weapon. [/B]
IIRC, the Rapier cannot be used to Strike a Weapon (or Sunder). It is Piercing damage, and Strike a Weapon requires Slashing or Bludgeoning damage.