Right from Mr. Levine's Guide#4....
Wester Bros. was a wholesaler and importer of German and U.S. made knives, located in New York. They were affiliated with Jacoby & Wester the U.S. agent for Wester & Butz, a German manufacturer. Looks like they went out of business around 1967.
Maybe Mr. Levine will jump in with more information, as I'm just paraphrasing from his book.