What KC 61 said will work fine on your knife and I’m sure you would be pleased with the results, however there are other methods and other materials that that I prefer to use. I will try to go through your points #1 through #6 and give you my methods and my reasoning for them.
#1 – Warm soapy water using Dawn dishwashing liquid is a great way to clean a knife. I would add to that old toothbrush or grout cleaning brush to scrub down in the blade pocket. After that I would rinse the knife in hot tap water. The heat will accelerate the drying process, but I would not soak wooden handles in water. WD-40 was made as a water displacement chemical. It is not primarily a cleaner or a lubricant. And since there is too much risk of getting the WD-40 into the wood my choice for water removal and cleaning would be 91% to 99% isopropyl alcohol. I know Kroger’s pharmacy carries 99% isopropyl alcohol, I think it’s about two dollars a pint. Not only is it very effective it’s an expensive. I like to use a syringe or an eyedropper to squirt the alcohol into the blade pocket and the joints. And I will even squirt some under the handles if I see dirt there and see them a little bit loose. Alcohol is not an oil-based product so it leaves no oily film and it is also a catalyst that will break down the chemical bonds between the oil in the water in the knife and help evaporate both oil and water.
#2 – Brasso works good on brass but I would try to avoid getting it on the wood. I would probably do the heavy cleaning of the brass even before cleaning the inside of the knife. That way you don’t have to use a lot of Brasso to take what little tarnish the soap will leave on the brass and the little bit of Brasso that you get on the wood will come off when you wash the knife.
#3 – The difference in the color of the wooden scales is probably not significant. Unless it is obvious that one of them has been discolored by an outside agent then the difference may simply be a difference in the color of wood that was installed on the knife at the factory. I am typically not a fan of using linseed oil on any wooden product I’m going to have my hands on. Linseed oil tends to have a very strong smell and it tends to remain tacky and never drying completely which is why it makes such a good word preservative. I don’t like the tackiness of linseed oil on my hands nor its tendency to collect dirt so I opted for a finish that will give me a fully dry finish. If you wish to use an oil finish, I would recommend Formby’s Tung oil finish. Typically I rub a very light coat on with my fingers and allow it to dry completely before adding another coat.
#4 – I assume you do not have a buffer or buffing compound to use on the blade therefore your option to try and clean up the blade with sandpaper? My first choice would be with ScotchBrite wheels then various abrasive rouges in stages to polish the blade. I understand if you don’t have a buffer then sandpaper is a decent method. I often use sandpaper on a flat surface both for steel and for other materials. The flat surface I use is a finished side of a piece of micarta. I have a bar of micarta that is about 1.5” wide X 2.5” tall X 12” long. I clamp that in my vice and use the finished 1.5” finished surface along one side as the backer for my sandpaper. I clamp 1.5” inch strips of wet or dry sandpaper along the top of the bar and that gives a good flat surface for sanding and since the steel is harder than the micarta if you happen to slip and bang the blade into the micarta sanding block it will not ding the blade like a steel backing plate will.
On the other flat side of the micarta bar I have glued a strip of heavy leather approx 3/16” thick. This is where I would do most of my cleanup of your blade. If your sandpaper is backed by nothing but a hard surface you’re going to have very few points of contact. This is fine if your desire is to make that blade perfectly flat, but you are going to go through a lot of sandpaper and little lots and lots of time. By having the leather backing on the side of the sanding block the blade will sink into the leather a little ways and you will have much better contact between the blade and the abrasive, very much like a buffing wheel. It will get your blade cleaned up far quicker than using a flat hard backer. Also that blade was probably hollow ground from the looks of it so you will not be able to send the curved lower portions of the blade with a hard surface backer.
To start with on this I would probably use a rubber bar as the backer for my sandpaper. They make them for use in the automotive industry with wet or dry sandpaper. Since they are rubber though water or oil does not affect the backer and they are stiff enough to do a good job of making the abrasive cut. The brand I have is called Dura Block, although I can’t find the full name because I have cut and the blocks up into smaller pieces to reach special and unusually shaped areas. You can buy these Dura Blocks in several different sizes and shapes round, a rectangular bar, flat bars and even shaped bars to use as backers for your sandpaper. They are used in the autobody industry for sanding small areas around contours or chrome pieces.
https://www.autobodytoolmart.com//dura- ... 20Products
As far as your starting grit of sandpaper, I began with the finest abrasive that will remove the marks. Remember every piece of sandpaper you use is going to make its own marks on the blade so the finer you start the better, as long as it is getting out the scratches in the blade.
Personally I would probably start at 1000 grit first. I use a piece of Dura Block as the backer for my sandpaper and I use a light oil on the sandpaper to help it cut faster. 3 in 1 Oil would be a good oil to use for sanding although if you can find a light weight cutting oil that would work even better.
If the 1000 grit is working well then just continue on up the line; 1200 grit, 1500 grit and then 2000 grit and you have worked through most of the common grits that are readily available in wet or dry sandpaper. If the 1000 grit is not aggressive enough I go down to 600 or 800 grit.
Now you mentioned polishing the blade. 2000 grit will be for from a polished blade but Jantz Supply carries 3M polishing paper which is a different type of abrasive it doesn’t cut like silicon carbide does. It has a much finer scratch pattern. It comes in the following grits: 400, 600, 1200, 4000, 6000 & 8000. If you really want to put a polish on that blade I began using 3M polishing paper after I had worked through all of the wet or dry sandpaper up to 2000 grit.
With the polishing paper I go back down in grit to 400, then 600 and then 1200 grit. This is to remove some of the scratches left by the 2000 grit wet or dry sandpaper that will be much deeper than the scratches even made by the 400 grit polishing paper. This is the process I use even on sanding brass or bone. If you will then still using the Dura Block as a backer for the polishing paper I work through all six grits of the 3M’s polishing paper and by the time you get to 8000 grit, it if you have done it properly you will have nearly a mirror finish on the blade. You might even think it’s a mirror finish but 30 seconds on my buffer will convince you that you were wrong. But this method is effective and it will give you a NEAR MIRROR POLISH finish. It is however very labor-intensive and very time-consuming.
#5 – To sharpen and oil the knife –
Assuming you don’t have a method of sharpening you can go back to that block of micarta and using the smooth side and strips of wet or dry sandpaper you can sharpen the blade. Just be sure that you sharpen away from the cutting edge and not into it or you will slice through the sandpaper. I would probably start at about 220 grit if the edge is not too bad. If the edges really bad I might go down as low as 120 grit wet or dry paper and I will definitely sharpen the blade using oil. A light cutting oil would be best but a light machine oil like 3 and 1 Oil is also adequate. I have sharpened commercially for years using 150 grit sanding belt but the result of a 150 grit powered sanding belt is much finer than 220 grit hand sanding. Look at the results that you get, it depends on what suits you best, you may want to go is fine is 400 grit, but that call is up to you.
The only knife oil that I recommend is Quick Release Oil simply because it works far better than any other oil I’ve ever used on knives. In just applying Quick Release Oil to an old knife, even before cleaning, I have seen snap return to a once lifeless blade. You can order Quick Release Oil from the Latama website.
https://latama.net/pages/quick-release-oil
#6 – I think the Maguires leather treatment would be fine on your sheath, You might do a couple of coats if it’s really dry.
I think that’s the majority of your questions. If you have any more be free to post them.
Oh, I forgot #7 -
WELCOME TO AAPK! 
Bench Block evh Solid Steel about 3 inches square Or Similar item can be Used.. For that professional look.. Joe
