This extra Vav seems to be the adopted Nusach of choice for all Ashkenazim (Edot Mizrach and Aram Sova do not; their beracha begins differently). I can only imagine there are earlier girsaot without the Vav. When did this version come into being, and what does it mean or add to the text? Is this beracha somehow connected to the previous one?
The beracha of ולמלשינים has the extra Vav as well, but I don't believe these to be of the same type, since ולמלשינים has been through significant censorship, so the version we have is necessarily a truncated form. (Note the Edot Mizrach version of למינים ולמלשינים.)