While I was sitting on the toilet reading the weapons booklet that comes with the limited edition of Destiny I came across something xurners won't be pleased about... on page 44 it states Gjallarhorn will not be given out. It must be "earned".
haha
Edit*
I understand Xur has sold it, but if you had enough strange coins week 2 you "earned" it.
-
I mean, completing the daily heroic story, which somehow dropped a legendary engram, that turned into a Gjallarhorn doesn't really feel earned... But hey, I'll take it where they come.