I expected Pan’s Lute to be in the Soulforge. Really, I don’t see “Crescendo” and “Garland Staff” there also, but Crescendo is in the Shop (for some $$$), and Garland Staff will be available tomorrow because it belongs to The Warrens. But Pan’s Lute?..
I believe Pan’s Lute is rewarded when you reach the mastery requirements for it (26 green & yellow). As such, it wouldn’t be in the soulforge.