Well, I ain't gunna give you something by making it up. The wording is kind of funny on these skillets; "YOU CAN GET IT OF WERTZ AND SINGER CO. MIDDLETOWN, O."
I would think you could get it "from" instead of "of" but I think they both mean the same. Perhaps someone in Middletown (historical society) can give you some info. Do you think they were a department store? Strange that no other similiar type of Wagner skillets seem to exist as well as more Griswold advertising skillet such as the No.2 Rau Bros.
There; something, if not much.
Steve
And, if you get desparate make a phone call-
Steven F Wertz - (513) 423-7078 - 145 Euclid St, Middletown, OH 45044