Ive had The Taken King DLC for about 4 weeks and XUR still hasn't sold one new gun. Also, I've only received one new exotic weapon which is the Fabian Strategy from the gunsmith quest. I wanted the dlc for mostly the new guns because they seemed so awesome but I've only got the Fabian Strategy which is kinda annoying.
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Purchase three of coins from xur. Better outcome of weapons. The chance of getting the exotic may be lower.