Jag tycker inte att detta är helt klart. Jag är inte heller säker på om jag ska använda spoiler-taggar här, så jag ska spela det säkert.
Shadow
is Baldur, a god and son of a god. It's possible the sacrifice empowers him somewhat, though Baldur is not a god of war per se. Recall that after the battle, and after he takes the coin back from Laura, he runs into Sam Back Crow. She is with a girlfriend. He slips some flowers into her hands but neither Sam Black Crow or the other girl see Shadow. So he's "behind the scenery" as it were. Perhaps that was partly a result of the sacrifice, though this is highly speculative.