I knew a Brunhilde, who was always called Bruni. Nice person; and an interesting character in mythology. Kriemhild sounds good, but only for a dairy cow; I know it's got nothing to do with cream, but the sound is just too powerful. Sieglinde appeals to me, though I'd prefer it with just the two syllables: Sieglind. (And Sigrid is even better.)
I don't mind "heavy and unwieldy" as such, but I do have problems imagining a Sieglinde with an iPod, chewing gum! They fit their own stories so well that there doesn't seem to be a good point of contact withour world outside those stories.