>PS & WC
These are just the initials for the same company, Peck,Stow & Wilcox Co, AKA Pexto
The 'Pexto' martk was registered in 1914, your wrench may be from before then....
From AA: "The Peck, Stow, & Wilcox Company was organized in 1870 by a three-way merger of the Peck, Smith Manufacturing Company, the S. Stow Manufacturing Company, and the Roys & Wilcox Company"
is it this wrench?