I appreciate the route the author chose. Not very heroic, not very dramatic coming from the epic main character, but it was a realistic result. Thorfinn was blinded by bloodlust and revenge ever since he followed his father's killer. He was doing dirty work, killing many people, dirtying his hand, and for what reason ultimately? He didn't have a single person to guide him, to nurture him, to teach him anything. It would only be logical his current self isn't capable of avenging his father.
Brilliant!