UNIQUE
From Anarchy Online Wiki [AOWiki]
UNIQUE in an item's description means that you can only have one of the said items per character. That is, you can have only one such item, no matter if it is in your inventory, backpack or bank. They cannot be sold through player shops.
This applies only to the items' ID. There are a few items with the same name and different IDs (like Notum Ring of the Tree). Different QLs of an item sharing the same ID, you can't collect them at different levels.
