Lost Glory

You'll start this quest in the Royal Hall at Jorvik. Approach the throne and speak with Moira. She'll tell you that Halfdan is pretty bummed out about the whole Faravid situation and might be found in a small village called Picheringa, which is east of Jorvik.

Head over to Picheringa. You'll find Halfdan sitting on a bench in the southeast part of the village. Approach him and start chatting.

Halfdan's feeling pretty low and is a bit miffed at Eivor for not being told about his brother Ivarr's death. Eivor will try to snap him out of it, but the next step is to go to Dalby Forest, northwest of Picheringa, to find Halfdan's hound, Beonton. Halfdan's hammer should be nearby too.

Once you reach Dalby Forest, whip out your raven to scout around for Beonton. You'll find Beonton protecting the hammer from three wolves. Take care of the wolves, then interact with the hammer to pick it up.

With the hammer in hand, make your way to Scarborough, a coastal town to the southeast. If you've been there before and synced up a viewpoint, you'll spawn right above Halfdan. Either way, once you get there, you'll find Halfdan on the cliff edge. Approach him to trigger a cutscene.

During the cutscene, Halfdan will ask Eivor about how his brother Ivarr died. You'll have two dialogue choices:

The choice you make here depends on whether you gave Ivarr his axe as he was dying. If you did, choose option one to tell Halfdan his brother died a warrior. If you didn't, choose option two to say he died a coward. While this choice is about staying consistent with what you told Ubba, it won't actually change the quest's outcome.

After the scene with Halfdan, he'll ask you to light the beacon at Scarborough. Climb the nearby tower and place the torch near the beacon to complete the quest.