Greetings,
If you throw the Eye of Anzu at the very end of the fight, Eye remains and can be thrown at another player till next combat begins.
Happened at normal difficulty, we have thrown it at each other couple of times for fun, but when trash was pulled, buff has faded.
Don't know how it can be used, maybe zone out with it for lulz if it's possible, or have multiple debuffs at encounter using evades (for WoL/WL abuse). Sorry for the engrish, not my native language