Æsilborg (short form Æsil) is a Valkyrie. Known to the Aesir as good at killing things even by Valkyrie standards, and having all the subtlety and political savvy of a particularly dense rock. There are plenty more Valkyries where she comes from and it is widely understood by pretty much everyone but Æsilborg that she has been sent to Midgard essentially to play the role of bodyguard/cannon-fodder.