You are to feed Arngrim 5 Disembodied Jormungar, then return to Arngrim's frozen image in Dun Niffelem. You must go to the Valley of Ancient Winters and use Arngrim's Tooth on the Roaming Jormungar there. Once they have become disembodied, you must fight them until they are weakened.
5x Arngrim's spirit fed
Arngrim's hunger was legendary.
Even in death, his expression is one of famished yearning. You find that just looking at him is making your stomach growl.
It is said that throughout his life he was never truly sated, and that there was absolutely nothing he wouldn't eat. You wonder to yourself if there might be a way to feed the old king.
No sooner does the thought enter your mind than one of the massive frozen teeth falls from Arngrim's head, bounces off of his beard and lands in your hand.