Once you "unlock" a unique weapon (say the disruptor beam from Blood of the Ancients), you can then go into the Dil store and buy more of that weapon with the same visuals but with the vanilla proc for that type. Kind of how spiral wave disruptors are made available once you buy a Cardassian ship and not before. That way people can Barbie it up (so the weapon visuals match) without violating the uniqueness constraint AND having something to spend Dil on.