In an unfortunate "accident", I once disarmed a pristine bonded blade of the torturer when it was still possible in pvp and removed the pristine tag from the item.
Being disarmed really did kill pristine status when BoE was new, since disarm code literally deletes your weapon and creates a copy in your inventory, and since BoE pristine status code only triggers when an item is looted from an NPC corpse (which also made it a pain to reimburse pristine status >.<). The more you know!