An Arthurian romance by Chretien de Troyes, [Eric and Enide (Arachnid)--guessed by Gaberax)]
A hubcap that works automatically, [spinner (guessed by Gaberax)]
A snake who is on the right side of the law, [Adder cop (Attercop)--guessed by Gaberax)]
O canst thou now tell me what truly I be?
Answer: A spider. (Guessed by Gaberax)