jup, aydas neclace need to have tag unique..since is not much point of having them more , since they are usless, other that quest :)-
and i discovered bug with him, if it happen to have him as loot (funny my first copy was from wolves and not humans, another bug imo too) and you just clock on loot icon, quest will not progres, you actualy need to click on icon of that amulet to advance in quest.
and similiar proble is with that book/brandy - i acidentaly buyed more than just one - and now they are usless in my item..i will just dump them :). they should deserve unique tag too.
and sure, yeah i will love if ayda neclace will be (later?) usable by her.
and it is similiar with ayneris rapier - will love if it will be usable only by her and not by anyone.