I just found a part sentence saying
"Attractive and affectionate to oneself"? 

Does that mean your attractive to yourself?


Question: How to prevent the "Too awesome to use" syndrome
Answer: A simple solution would be to make this special item available in-game for a limited time. 

For instance in 2012 Jagex (creator of Runescape) added a special item called the "DeathTouched dart" it could kill any opponent with just one hit. It has been said that it will be removed on some unspecified date.


  http://runescape.wikia.com/wiki/Deathtouched_dart


That way, most players used their darts and their purpose has been fulfilled.

Another example from my game experience comes from an old game called "Star Wars Jedi Outcast Academy II", I remember that I aquired some rare items like Seeker drone, which were supposed to help you fight your enemies. Due to their rarity I have kept them until the end of the game, hoping they can help me fight the final boss, but to my dissapointment it hasn't even left a scratch on him. In that case I would simply make them more common.