A true burnishing with a 'burnishing tool' will give the surface a very high polish. It also very slightly compresses the surface of the metal.
The 'Burnishing' of some metal parts prior to finishing (like case coloring) was sometimes done with fine wire wheels and the parts lightly coated with oil.
A blending of the surface polish lines results along with any deep marks that were missed show up glaringly.
Some burnishing tools are used to put only narrow lines into the surface of tight fitting parts to allow for lube. The same idea that engine turning/jeweling can be used.
I've seen an old picture in the past, probably very early 20th or late 19th century of European(?) gun factory workers using a burnishing tool with a long wooden handle of what I'd estimate to be 2 1/2ft with a burnishing tool in one end.
The worker placed the end of the wooden handle over his shoulder and pulled down on it with both hands burnishing the part with the extreme pressure that must apply.
Probably a fairly fast method too for someone with some experience.
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There are pickeling solutions and there are etching solutions. Pickeling solutions are used to remove oxidation & scale from heat treatment in most cases.
It will leave the surface with a somewhat brighter look than the etch.
Etch is used to matt a clean surface.
Some solutions will do both if left in long enough. Sometimes it's not the end result you wish for though!
Steel can be etched more evenly and safely with something like Ferric Chloride than most acids. But acids are what many think of when a steel etch is called for,,and with some form of heat which can lead to problems quickly.
Scrapping can leave any surface finish you wish. It all depends on the polish given to the tool doing the work.
The cut of the tool in the material is no better, no shinier than the polish given to the sharp edge on the tool.
Same as engraving tools/chisels. Shape and polish them to 600/800 or even 1200 and you'll have a nice but somewhat dull look to the cuts.
The same cuts will look like their name-sake if the tool is polished one step further on a ceramic plate with diamond paste.
