You get rapier slightly after 80 dungeoneering. Maybe up to 100k xp off, which isn't all that much. And rapier is definitely worth getting, once you use it, its impossible to go back to whip. It's awesome for anything, does exactly what a whip does, but better. And the recharge cost isn't that much considering the time you're saving using it, and it's always more fun seeing yourself hit a 500 rather than a 450.