If you're grabbing the gla/mara gear, you can't use it. Lancer should be able to use anything else (tanks can use everything, physical dps can use all but tank gear, casters can only use cloth). Make sure your class is in the list.
Also make sure you're high enough level. That eyepatch is level 5 or something. If there's a GREEN X by the item you can use it, but aren't high enough level. A RED X means your class can't use it.
Or you're not a lancer, and you rolled a scholar instead or something.