A few years ago I saw an epic fantasy movie involving two twins. I think the twins were elves. The female twin was good and the male twin was evil. They were connected, so that hurting one of them would also hurt the other. The good twin had some powerful magical artifact that the evil twin was trying to get ahold of. There was a big battle at the end in some kind of place with clockwork. The female twin finally stabbed herself to kill her brother.
I think it had CG, so it should be relatively modern.