They say that Shartan's followers stole whatever they could find to make weapons. They fought with knives of sharpened stone and glass, and with bows made from broken barrels or firewood. This bow was ox horn, made in secret over the course of months by a slave who worked in the slaughterhouses of Minrathous. The slave's name has been lost to history, and the verses that spoke of his deeds stricken from the chant, but the weapon endures. —From Codex entry: Dark Moon
This shortbow can be bought from Varathorn in the Dalish Camp, but only after completing three main quests after Lothering. The weapon will become inaccessible if it is not bought before The Warden resolves Nature Of the Beast through the option killing the elves. Resolving it by killing the werewolves or by making peace between the two groups will allow the weapon to remain accessible.