I saw this thread yesterday, and took some time to consider it before responding.
I started my knifemaking career during what I call "The Dark Years"... when EVERYTHING was a "secret". Knifemakers did not communicate with each other, and it was considered offensive to ask any accomplished knifemaker anything. I can't count the number of times I was told "That's a secret!" or "I can't tell you that!"
One instance that shaped me was.... when I first started, I called a well known Bladesmith with a simple question of "What type of solder should I use?" His response was... "You'll have to come to my shop to get that information." and after a brief pause stated... "But it will cost you $500 per day to come to my shop." At that time I was still rolling up pennies to buy milk for my baby girl.... it might as well have been a million dollars a day! Many years later, that same individual walked up to me when I achieved my MS rating, and whispered in my ear "We've been waiting for you." Obviously he had forgotten his past, but I had not. That incident, along with many similar ones, made me who I am, and gave me the feelings/attitude I have towards sharing information.....that being, I have no secrets!
What information in your shop is proprietary?
I'm likely gona make some hackles raise with this thread!

NOTHING is proprietary! My personal view is... There are no "Secrets". My feelings are.... if a knifemaker ever says something such as "That's a Secret", or "I can't tell you that", just tell them to have a nice day, and walk away. Those are the people who.... 1. Are afraid of you. 2. Don't have anything on the "back burner", and are concerned that you are going to take something from them. It all boils down to an ego thing, and the one thing that I refuse to tolerate, or deal with, is ego.
If you put much time into a method that sets your work far apart from others, do you share it?
In every single Bladesmithing/Knifemaking situation where I teach. Whether I'm typing here on the forums, talking on the phone, teaching a student in my own shop, or teaching/demonstrating at a hammer-in/gathering, nothing is held back. Bladesmithing/Knifemaking is an exercise in learning, no matter how long you've been doing it.
What I have come to realize is that no matter how much information I present, I am incapable of relating all the nuances that go along with any given method or technique. What this means is.... no matter what I teach/show an individual, or how many times I do it, there are "little" things that I can try to vocalize and show, but until the individual(s) experiences it for themselves ( often a number of times), it doesn't "click". And when it does "click"...it's going to be a variant of what I specifically do. Two examples are grinding and hand finishing. With grinding I can vocalize and demonstrate till the cows come home, but until an individual actually does it, feels it, hears it, and sees it first hand, most simply cannot grasp all the nuances....it takes time and practice to build the skill. With hand finishing the example is what I call "shadow scratches".... when an individual thinks they are done, but then I look at what they've done is various angles of light, and see tiny/underlying scratches that were missed. Again, it takes time and practice for the individual to develop/understand the nuances. This also applies to any number of methodologies/procedures within knifemaking.
When I worked in product development we had to sign non disclosure agreements for EVERYTHING...from products them selves to mechanisms, materials used in a new way, fabrication processes, etc. They would not even tell me the flagship product they were developing until I signed on....
That situation often exists in modern custom knifemaking too..... but tends to be when a custom maker is dealing with a production entity, such as a factory deal, or other "production" type situations. I'm sure there are similar things that go on in the custom knifemaker realm too, but unless an individual is really insecure, I can't imagine a custom maker requiring anything like a non-disclosure agreement with another maker.
I think some of the ingenious guys here must sit on some techniques? It's one thing to share good solid info in general....but what about the stuff that gives your product its personality?
I'm sure some do, and others THINK they do. (back to the ego thing) Personally I believe I can share anything and everything about what I do, and how I do it. What gives a Knifemaker's product(s) it's personality is the individual maker....not the methods or techniques. I could have 3 different individuals sit over my shoulder on any given project from start to finish, then those individuals could ATTEMPT to replicate what I did, and there will be 3 different/distinct outcomes. There are going to be some slight variances in each, but it's those variances that make one maker's knife readily identifiable from another's.
The guilds of old Europe kept a lid on the local knowledge
And they still do! The first time I ever taught in Europe was a little spooky to me. It was in a shop located about an hour outside of Bitburg, Germay. I was there with a friend/interpreter, and was conducting a weekend "hammer-in" on Mosaic Damascus. The shop was located in the center of the village, and once everyone was inside (about 50 people), all the doors were locked, and all the shutters on the windows were closed. I started wondering if I was in a Criminal Minds episode.

I had heard they would be somewhat secretive about things, but never realized the depth of it, until I was there.

Every other teaching experience I've had in Europe has been similar.
A stark contrast to my experiences in Europe, have been teaching in Canada. Where as in Europe it's all a secret, and the U.S. there is always someone taunting... "That's not the way to do it!", Canadians are wonderful! They are open, genuinely interested in learning, and just a great bunch of people. I've never had a single individual in Canada ever shout out or murmur "That's not the way to do it!" Where as, I've never not had that happen when teaching at any event in the U.S. Coming from a guy who's job for much of his adult life was to kill people and break things (my military career).... I always find it an interesting diversion to see/experience how different countries/cultures act/react in similar situations.
I'm thinking that as a guy's skill level gets into Artiste territory he most likely has a few trade secrets?
I think it's just the opposite...at least for me.... I think by the time an individual has had enough time doing it, to obtain a given skill level, he/she realizes just how much more there is to learn, and also realizes that because of the artistry involved, it doesn't matter what's shared.... others simply will be unable to
copy the nuances.

I suppose that, in itself, could be consider arrogance, but for me, when I realized I could do this for a half dozen lifetimes, and still not know it all, it gave me the attitude that if I were to die tomorrow, with an idea in my head, what good was the idea in the first place? In the U.S., we are a culture of competition and ego..... we often times let those things define us, both personally, and in what we do. I've been down that road, and found that I am a much happier, healthier individual when I can minimize the impacts on my life of either. In the end, it's just making a knife. It's what I do, not who I am. :3: