That's quite new for a brand new item... maybe you found something someone else lost?
You may want to take a look at this:
http://wiki.battlemaster.org/wiki/List_of_Unique_Items/Top_Ten_Prestige
Nope, was definitely a new item - didn't even have a page and was in good condition.
The wiki page has seen several new items with very high prestige rating. I even purchased one. Such items are usually books from what I've observed. I think those are coming from that discussion about unique items we had few months ago.
It was indeed a Book - I wonder what the special thing is about books?