Not explicitly Norse but the Celtic chooser of the slain? Sounds like a Valkyrie to me.The Morrigan - Shape-shifting Celtic goddess of War, Fate and Death. Story in "The GODDESSES / Psychology of Female Power"
Selene: Greek Goddess whose presence is felt when the moon is full. In the triple phase of womanhood, Selene is the fruitful mother at the Full Moon who stands proudly between the maiden Artemis at the Waxing Moon and the crone Hecate at the Waning Moon.