Back before WWII there were many gun makers in Europe who made cheap handguns by the thousands. I've never heard of a Warnet. I would say yours was made in the 19th century. It's very interesting that you have the capture papers for it, that makes it worth a lot to your family. These guns seldom have little if any collector value. Keep it to remember your father's service.
Is this piece similar? It has worse finish condition and does not seem to have a letter of provenance. It seems to be a bit older, with an older style loading system. However it shows there is a market for this brand.
+1 to what Stand Watie said--when my grandfather died, his good-for-nothing drunk son (my uncle) hocked his old AF service sidearm for rotgut money, and I know that I will NEVER forgive him for that. Ditto the avaricious and/or alcoholic relatives back east who stole and sold off Uncle Frank's collection of captured Nazi officers' pistols and the weapons he stormed Mauthausen with.
As far as I'm concerned, they're all dead to me, and I'm only TOLERATING dealing with them as far as necessary until my grandmother's estate is settled.
Fwiw, this subject is personal to me, as my Uncle Jack's treasured Mauser Broomhandle, (that he took from a German CPT who surrendered to him during WWI) & was willed to me) was stolen DURING his funeral in 1962. = I've NEVER forgotten that & am still watching the gun-shows/classified ads/auctions within about 100 miles for it coming up for sale.