What was the point in having Finehair rape Bjorn's 2nd wife

If he and Bjorn was both gonna die in the battle? I don't get why that needed to happen exactly, at first i thought it would build to Bjorn finding out and going on a crusade to kill Finehair and get revenge, or even Bjorn's wife seeking her own vengeance out and killing Finehair.

But both people the rape had any significance on in the story are now dead so it feels like that was kinda pointless for the story.