Plomb tools changed their name to Proto (I believe in '47 or '48, someone correct me), the popular and well-respected industrial tool brand. I'm new to the forums here, but Plomb/Proto seems to have a lot of love on here. I know I'm a big fan.
Actually, WF stands for Wright Field [WWII Government contracting location]
(1) WF was used to precede the identifying number on hundreds of thousands of Plomb tools that were used by the Armed Forces during WWII. These numbers did not correspond to the Plomb catalog numbers.
(2) The words "War Finish" were stamped on some Plomb tools produced for the civilian market during the WWII era and carried the standard Plomb catalog numbers.