My references show the "OWA" as a .25 automatic made in Austria, after the First World War to the mid 1920's. Two different models, with mechanical and slide legend variations. Supposedly well made but over engineered for what it was i.e. basic run of the mill vest pocket .25. Value is based on demand and condition?
These were interesting little pocket automatics. They sort of looked like the old Pieper but the actions were simular to the Clement. O.W.A. only produeced these pistols from 1920 through 1925 and then faded away. As rufe-snow mentions they were way to complicated for what should have been simple blow back pistols and were eaten alive in the marketplace by the Browning and Ortgies pistols of the era. By comparison the Ortgies had just 29 individual parts (and not a single screw) while the OWA had 43 parts! The Browning Baby has 33 parts if you are curious. The instruction manual of the OWA boasts such things as ..."top quality materials, machined with percision instruments. The astonishing ease with which the OWA can be dismantled, permits thorough cleaning of the pistol even by laymen". The diagram does indeed make take down appear to be a snap...real life is often different! A rendition of a test target shows very impressive accuracy at 10 meters. There is some collector interest in these European pocket automatics...I LOVE Ortgies pistols myself. I would say that your OWA in nice condition would fetch around $200 to $250, perhaps more if it were an exceptional example. I hope this helps you.