"...e.g. earnestness and honestness"

Hey, shouldn't that be "earnestine"? And what is the difference between "impotence" and "impotency"? I'm sure there's some hideous joke in there someplace but I haven't figured it out yet. Anyway, I've also seen "competence" and "competency". And why should the words "crisp" and "crispy" both exist?