Board Thread:General Discussion/@comment-75.141.243.26-20140213002350/@comment-2255188-20140213045754

Issue 10 answers it partially. The pureblood Wesen are the basal ones (they share a common ancestor, too). All the other Wesen are descended from the purebloods. So far the only confirmed pureblood is the Maahes, which are basically Nemean lions, practically impervious to mortal weapons. It's also been revealed that purebloods generally are more godlike.