Requiem for a dream
i just knew someone would suggest it before me. ever since they used it in LOTR (advert or movie not sure) every body associates it with medievil, but in fact the song is called zooyork and from a movie about drugs entitled Requiem For A Dream (hoorah for useless knowledge).
As much as i love my metal, i'd personally stay away from genres of acquired taste, not all people like metal, but most people can tolerate classical/orchestrated music. However, I could imagine fighting as nords to the immigrant song by led zepplin
(I know its rock and yes i'm being an idiot).