That's a nightsaber. Most people who have them are Night Elves who got them early and just kept them. I can't think of anywhere outside of Teldrassil and Darkshore that you can get one off the top of my head, but I'm sure there's somewhere. You can eventually get owls elsewhere, so I assume there are sabers elsewhere...just the same, a cat is a cat for the mostpart, and there are PLENTY of cats in the game.
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Only the exceptions can be exceptional.