While I agree with James Risner, this does make me wonder about Mage's Disjunction.
Would a sheathed sword worn under a cloak be unaffected as the mage has no line of sight to it?
Debate over which items are or are not affected could occur.
"A burst spell affects whatever it catches in its area, including creatures that you can't see. It can't affect creatures with total cover from its point of origin"
Granted, it says creatures, but I'd think it'd apply to objects too.