I have a solid handle silverplate pie/cake server with stainless blade with a maker's mark of WB over W with a line in between. From what I have been able to find, it is Wallace (see the last photo), but I can't find a Wallace pattern matching this one.
Trev, Thank you for the images. I have come across some of the plate on cast steel with this mark before (as shown in the advertisements) -- not anything I'd want to eat from. It was very worn and rough.