Anecdotes have it that Walter was a barber who started selling glass by mail-order. Same anecdote tells that Orrefors glassworks and Kosta glassworks did not sell to him, but SEA and other "small" glassworks did. (and that he also imported)
Considering the number of pieces found, his operation must have been quite big - or he was active for many years.
There were several former employees who used their hometown (well - home-village) name in their small(ish) firm's name to get some extra "fame".
As to Walter's artistic or engraving skills I have no idea.