And sure, you can argue that it says it in the quest, but what Weedhopped said above is absolutely true, you do have to type "delete" to destroy other BoAs, and I am pretty sure there is no precedent where a quest takes away something like this, generally you have to turn the quest in to GET the weapon. It seems like poor design. At the very least you should be able to get it back, like a buy back from vendor option. They have those for a reason.
Also, even if they can't restore the quest item, shouldn't be that big of a deal to restore the mats so you can craft another one.