Studying pictures of original rifles and guns, as well as contemporary stuff, and having the opportunity to study them in person, are two different experiences. When a "Great" one is picked up, it is obvious and apparent instantly, yet, others may grow on you, and achieve that level over some time. There are levels of "great" too, but those to which you can slap that moniker immediately, have all of the features described by you already, and a quality that evokes emotion. That spiritual or mystical quality is the character, soul, and personality of the piece. I like to think that it may be more evident to a builder than anyone else, because it is the essence for which we strive. A non-builder obviously can have deep appreciation too, of course, though perhaps not at the same level. Until a person has children of their own, they can't appreciate that depth. And the same analogy may apply to these fascinating things.
It's certainly not a simple question, Jim.