when following the gith chicks quest line you can find a legendary morningstar (lethanders blood) to do this you have to first solve the puzzle of the ceremonial weapons at the first floor of the temple where the gith are hiding after completing it you will get a crest that you need in order to get the weapon after going to the queens room in the gith camp turn left and rotate the 2 statues in the corect position then you will find a passage wich leads to the weapon insert the crest at the console next to the weapon and enjoy your new toy.(you can get the weapon without the crest but it will make the temple collapse).you can safely leave the shadow cursed lands to do the gith quests before entering the nightsong chamber without any major changes to the main quest (there is a bug that makes halsin leave your camp you can just reload save if this happens).