As the Norse and English sources show them to us, the walkurjas are figures of awe and even terror, who delight in the deaths of men. When he failed to recognize Her and rejected Her, She told him that She would hinder him when he was in battle. She appeared to him on at least four occasions and each time he failed to recognize Her. 1. When She appeared to him and declared Her love for him. After he had wounded Her, She appeared to him as an old hag and he offered his blessings to Her, which caused Her to be healed.
Some people use menstrual blood, which is very appropriate.
Blood, especially menstrual blood, is a symbol of both life and death, fertility and war. Rituals should be kept simple. When you feel Her presence, you may wish to offer Her something of value. This can be as simple as some ale or as difficult as spilling your own blood. When I dedicated myself to Her, I meditated on a crow's feather and a candle flame.