It is good because as users of old cast iron we get to buy some superb pieces for a lot less money than a comparable Griswold.
It is bad because I think the old and Wagner Ware pieces deserve a little more respect.
Sometime between 19, the logo on several skillets (#4-#8) appeared at center, as it would also come to be seen on the later, "dual logo" National skillets Wagner produced.
Erie, Martin, BS&R, Favorite...collectors will be on those like stink on a monkey.
However, the Wagner brothers, Bernard and Milton, actually started making metal castings of light hardware for general stores back in 1881.
In addition, the brothers manufactured tin hollowware for government contracts.
This kept the cookware from direct contact with the top of a wood stove. Note if there is a sharp ridge or a hollowed-out section where handles connect to the bodies of skillets.
All these things provide clues to the age of your cookware.
The use of cast iron for cookware is centuries old and many of the vintage pieces can still be used today.