You CAN take this item to another server if you leave Legends.
Link to official FAQ: http://legends.everquest.station.sony.com/faq.jsp#Moving
Quote:
"Q: I already know that when I move a character to a Legends server I get to keep all my stuff, titles, faction… everything. But what if I cancel and go back to my old server? Will the unique items that I've discovered on the Legends server go with me?
A: Absolutely. Anything you earn on a Legends server you get to keep. We also wanted to point out that all items that are unique to the Legends server will be no-drop if moved to a non-Legends server on which such items are still not available. If at some future date those items become available on the servers, then any such items brought to the server earlier may become dropable if the Live version of the item is also dropable."