You could do something like I did to make a silent wrench.
function SilentWrenchImage::onFire(%data, %player, %slot)
{
WrenchHitSound.setName(WrenchHitSound_Temp);
WrenchMissSound.setName(WrenchMissSound_Temp);
WrenchImage.onFire(%player, %slot);
WrenchHitSound_Temp.setName(WrenchHitSound);
WrenchMissSound_Temp.setName(WrenchMissSound);
}