This was a quote from the poem Völundarkviða and really sparked my imagination. I looked into it a bit more, and it turns out part of the Valkyrie legend was that when they come down to earth they often take the form of the swan.
The outfit won't be entirely swan, and nothing else. I want to mix the stereotypical Valkyrie influences into it all, and rough it up a bit. After all the job of the Valkyries was not a pleasant or lovely one, they were choosers of the slain.
There are several distinctive features in the swan. The orange and black beak, the long neck, nd the smooth white wings, probably being the most distinctive.