some answers
first i will sat the movie is very cool, it makes me want to see the second part and i will ;P good job man XD
now to who didnt readed nordic mitology ''valkyrie'' was the name of Odin's daughter
second the story is no confusing... valhalla was under a siege and a warlock tryed to usurp Odin's throne, and Valkyrie was defending it, then as she was losing, she enclosed herself in that kind of amulet, why it finished with the cop's father idk, but i think they are generations far of them and it was passed to every generation of their family, and they ''bad guy'' need murder her to take the throne.
third and last if im wrong please correct me