I didn't make separate art for them, but they were on the general information sheet: https://www.furaffinity.net/view/34654760/

Wyverns, like harpies, are from the lower class of society, as they do not have unique practical skills. They are considered a failed version of dragons (which are considered elite).
They fly poorly, do not spit fire, and are unattractive in face (muzzle?).
They stand out only with a poisonous sting at the tip of their tail and this is their only weapon. (which is actually useless in their peacetime).