I have not yet in over 17 years of honing razors EVER created a frown. I have fixed MANY.
Unless the warp is horrific it can be fixed.
Thank my stars I've never sent an old warped fine shaving French razor to you, it would return 'perfect' but missing a lot of metal and as such in my opinion never shave quite as well.
But we can all agree to civilly disagree.
Personally I will leave warp alone if the only ways to remove it all involve steel removal which in my opinion is not ideal. I have many vintage French blades with wonky bevels that all shave great.
the better, leave that steel in place and I'll try to move it around as best I can rather than to sweep it away.
Where do I go from here to get the bevel set properly?
Well, the French producers of the razors have always considered it a form of honing, and you can read on the French forums how long they go with only the paste.
It doesn't leave much slurry and yet it reshapes the cutting edge VERY fast, or at least my sandy textured bout does. Where did the steel go, if it left? Can it be that it is bending the steel and reshaping it without breaking it off? I do not know the answer,
There is a razor honing school, sir - in the trades practiced in Germany and France where they still undergo formal training as apprentices, and it takes years plural to even work on finished product which will touch a customer's hands a full decade before mastering.
This is getting good! Lol!
That's not how it works, (self taught) stonestrop; in Germany, they have many formal guilds such as cuckoo clock making, brush making, razor grinder, etc. Generally either the old companies will approach people in high school, or the inverse, and agreement is made to take on the apprentice for 2 years in exchange for some guaranteed time as their functioning employee. The kid gets education they can use for a lifetime and the company hopes they get a terrific long term producer. So it isn't like a HVAC or welder's school as in the USA, but it is strictly regulated internally to the guild members in the tests you must pass under which you present your skills to the masters under which you apprentice and they agree to certify you've achieved that particular facet of the profession. When you have passed all the tests and begin working true you do indeed get a certification, but this isn't a school and you can't buy your way in.
You must agree to servitude as paid employee for a prior agreed quantity of time, in exchange the company is paying for your learning because you are costing them time without producing finished product (yet). After you've done your time, you are free to work for yourself or another or as a freelancer in the trade, conditional to for example that your work must occur within specific geographical boundaries defined by the trade.
I do not believe, but do not know with certainty, that these guild grinders would ever agree to do to a razor with mild warp as you espouse. Otherwise, I would not own a beautiful and ever slightly warped mid-90s Wacker which looks as it does, it'd have come from the factory with your 'solution'. But let's play this the other way, as these folks don't much concern themselves with what the self taught experts outside of their regulated profession say is or is not the right way - *you* find me any razor grinder in Germany who would assign their name to your solution. I'll wait.
Actually I do know one guy at work who's a native German and from the NW Rhine state, I'll ask him tomorrow if he thinks he could ask somebody from home if they can find such a picture to assuage your concerns of your unquestionable formal expertise. I believe there is a grinding museum in Solingen and you can see such certification there, but they call it master grinder, encompassing razors, scissors, cutlery (no doubt these folks love the term "honemeister").