How do you get the rewards? If you are able to kill a boss for the first time outside of a quest, you will have the chance to get the rewards. By boss, we mean the weekly bosses:
Great Wolf King
The Count (Childe)
It is pure luck whether you get such an item and which one. You can not influence this. Some players have spent weeks trying to get the right items. The boss items and the unprocessed weapons are multiple items, but they are all equally rare, which is why we count them as a single item.