In Scottish/Gaelic Myth, there is a warrior maid by the name of Scathach (hence my username.) A weapon that she used was called the Gae Bulg, otherwise named as the spear of mortal death, the gapped/notched spear, or belly spear. It was a weapon with a barbed spear head which required anyone stuck with it to be cut into for it's removal, making it quite damaging. It was also said to be made of the bones of a sea monster, which I thought would be a very interesting weapon design. While reading on Wikipedia, I found this information and thought it would be apt for a Valkyrie weapon. Please feel free to use this suggestion as you please.