This item has state-based gating that prevents it from being equipped in certain
circumstances. For instance, an item might be for Warlocks only and you're a
Titan, or it might require you to have beaten some special quest that you haven'
t beaten yet. Use the additional failure data passed on the item itself to get
more information about what the specific failure case was (See
DestinyInventoryItemDefinition and DestinyItemInstanceComponent)
This item is part of a "unique set", and you can't have more than one item of
that same set type equipped at once. For instance, if you already have an Exotic
Weapon equipped, you can't equip a second one in another weapon slot.