There was a brand of Canadian tools called "Tecomaster", which was the house brand of the T. Eaton Company chain of department stores. However, their logo is quite different from this one, so I have to conclude that Teco was a German firm. The fact that the wrench isn't stamped "W Germany" suggests that it's pre-war. Below, pics of the wrench as I found it. Amazing what a little time in the sandblaster and on the wire wheel will do.