There really isn't much to do.  Just keep them out of serious humidity, and occasionally clean and oil them.  Despite myths about choji oil and other things, any high quality gun oil can be used.

Probably a stupid question, but I'm assuming that the swords in pristine condition were probably never Pacific war swords.

OST

As I mentioned above, WW2 swords can range from total crap to really desirable correctly made swords (called gendaito).

At the "low" end are the NCO swords (as you mentioned).  These are machine-made, and are generally not very valuable.
Then there are individually forged swords, but still relatively "mass produced" and quenched in oil.  These are not considered "true" Japanese swords, and would be called showato (not gendaito).
Then there are individually forged swords, traditionally made, and quenched in water.  These are generally good quality, and are considered gendaito. Some of these, like Yasukuni shrine swords, can be of VERY high quality and are highly collectible.

My WW2 blade is a correctly made nihonto (gendaito), and it is particularly interesting because it was signed by Emura Saku.

This blade has a pretty decent polish and had new furniture made for it, with fittings from the 1800s.







I paid just over $1600 for it, which is a really good deal, considering that it's not just a well-known gendaito smith, but it has really nice (new) furniture.

That is a common misconception.

Yes, all swords ARE registered, but only a VERY small number are not allowed to leave the country - those officially rated as national treasures.  All other blades can be freely bought and sold, and exported.

Like I said above, it all depends on what you are looking for.

If you want a high quality wakizashi (short sword) made in the 1600s, in excellent condition and with official paperwork, then sure, that can be found.  The example of the blade I just got from Japan that I only paid $1350 for is a great example.

If you want a katana, it's going to be harder to find something for around $1500, but can be done.  It might take longer to find, and it may not have official paperwork, but it's probably possible.

Sometimes, you find REALLY good deals.

As an example, I bought this sword for under $900.  It was listed on ebay by one of the dealers I mentioned above, but the description was incorrect.  He listed it as a wakizashi, but the pictures were clearly of a katana.  Plus, it has WW-2 furniture, so it could have been a shitty WW-2 blade.  But, I rolled the dice and bid on it, and got it for $880 (including shipping).

It turns out to be a katana from the late Muromachi period, around 1530 to 1550 (Tenmon). It is signed by Norimitsu, who is ranked Jo-Saku (“Superior” 3/5) by Fujishiro and who worked in Bizen (one of the classic five Koto schools).  The blade has a cutting edge of 66.5cm, and quite a deep curve of 2.2 cm.  It has a very classic Muromachi shape, and a quite long kissaki.  The blade has not been shortened, and has only one mekugi ana, so this is a very “original” Muromachi blade from the Sengoku (warring states) period.

So this is an intact Muromachi-period blade, with signature - and I got it for less than $900.  



... Of course, because I am an idiot, I couldn't leave good enough alone.  The furniture was clearly just some garbage furniture someone had found, and didn't really fit the sword very well.  So I decided to have new furniture made.  I had some REALLY nice fittings from the 1600-1700s, that I wasn't using for anything, so I figured I would have new furniture made using those fittings.  THEN, I decided that if I was going to have new furniture made, it would be appropriate to have the polish on the blade touched up - the polish was okay, but it could be better.  So I got on a polisher's waiting list, and after about a year and a half, he put a new "finish" polish on the blade (which cost about $900), and then I had the new furniture made (which cost about $1700).

So, it was a SCREAMING deal at $880 - but once I got done with the polish and the new furniture, it ended up being around $3500 (not counting the cost of the fittings)

Still, it is now very pretty.

+1

If you are patient, and wait around for "the deal" you can do pretty well.

Again, if you want a katana, it's going to be difficult - and you're going to have to make some serious compromises on condition and quality.  Even a wakizashi is tricky for under $1000 - especially with furniture.  As I noted above, I was able to find a cool Kiyomitsu blade for under 1000, but that's in a storage/resting sheath, and I had to haggle a bit for it.

But, here is a more recent example of something I bought:











This is an intact wakizashi blade with furniture, and I paid $941 for it (shipped) in 2018.

The signature is "Soshu ju Hiromasa" and the dealer believed it was from the mid 1500s.

Now, this is DEFINITELY a true Japanese sword from the 1500s to 1600s - so that would probably already meet your criteria.  The only real question (to me) is whether or not the signature is authentic.  The only way to REALLY be certain for sure would be to send that blade to a NBTHK (or NTHK shinsa) and submit it for official evaluation and paperwork.  However, to spend the $500 that would probably cost is not really worth it when I only paid $941 for the sword.

I am pretty sure the signature is authentic.  For one, Hiromasa is not a super-famous smith, and so if someone was going to carve a fake signature into the tang, they'd probably have chosen someone slightly more famous.    I also think the signature is authentic because the style of the forging pattern seems consistent with the Soshu school.  I have several other papered swords from the Soshu school, so I am somewhat confident.

That said, it is a little tricky to determine WHICH Hiromasa, since there were multiple generations that used the same signature.  Most likely it is the 6th generation Hiromasa (広正), who worked in the Tenbun period (1532-1555), in Sagami and signed „Sōshū-jū Hiromasa“ (相州住広正).  It could also be the 5th generation HIROMASA (Hawley HIR 273) who worked in the Bunmei and Meio periods (1469-1492) in SAGAMI, and is ranked JO-SAKU, and rated at ¥4M in Toko Taikan.  The 3rd and 4th generations of Hiromasa also signed Soshu ju Hiromasa, so it is possible that the blade is older ... but it is also possible that it could be gimei (i.e. a fake signature).

My guess (as noted above) is that it's the 6th generation from the mid 1500s.

So, less than $1000, and a really nice blade in good condition, with nice furniture.  So things like this CAN be found, but it takes a lot of time and patience, and some luck.

So how sharp are these collectible Japanese swords?  Are they ranging from dull to extremely sharp?

With a proper polish on them, they are very sharp.  All of mine are in good polish, so all are sharp.

This is true, and creates a big dilemma when you own a rusty blade.  Do you want to spend thousands of dollars having it polished, just to discover the blade is worth less than the polish you just paid for?

What some polishers can do is open a "window" - meaning they polish just an inch or two of the blade, so see what the grain and temper pattern looks like, to help identify the blade.

That's how it starts.  I am sorry.  

I honestly do not know.  Hundreds of thousands I think.

As a general rule, I doubt I would lose money if I sold any.  
First, because obviously they aren't making any more 1500s and 1600s Japanese swords, but the human population (and disposable income) is generally growing, so supply stays the same, but demand will probably grow.
Second, because I am obsessed with finding "the deal", most of the swords I have bought have been at a really good price, so I am certain I will not lose money if I sell them.

The few that I have "sold" have generally been trades (to close friends) for other things/services, so it's hard to really calculate what "price" I got.  

As mentioned in a reply above, there absolutely ARE highly collectible blades from WW2.  Yasukuni shrine swords are one example, but there are numerous highly talented smiths that made very high quality blades during WW2.  These blades would usually end up in the hands of highly ranked officers, or officers from wealthy families.

Even if they saw use in the pacific (and perhaps rusted a bit, or were just stained), they can easily be restored to perfect condition with a finish polish.  Because such swords ended up among higher officers, it's unlikely they saw much actual "use" - and so most are in really nice condition.

I once bought a nice-looking wakizashi for about $550.  

The shape of the blade is actually really nice, with a long point (kissaki).  The furniture is in decent condition, but the scabbard may have been painted at some point.  The handle is fine, but I think the rayskin might have been painted as well, rather than properly dyed.  The blade is signed Yoshiiye.



I couldn't find a Yoshiiye smith from the general period I thought it was from, so I suspected the signature is fake.  I scanned the blade and sent it the one of my dealers in Japan for their opinion, and they concurred with my belief that the signature is fake - and believe the blade is from the 1500s.



Still, it's a genuine Japanese sword, correctly and traditionally forged in the 1500s.  And I got it for $550.  

... but, that is definitely the exception, not the rules.  I have been quite lucky with some of the blades I have bought.  This is just to illustrate that if you are patient (and a bit lucky) you can find some sweet deals.

I think that's reasonable.  If you are lucky, perhaps as low as $800-$900, but it would take a while.

Most things you can find for less $1000 will have some problem, and you likely will not be happy with it in the long run.

@MirrorMirror and @DK-Prof

Are the steel of the old Japan and the modern-day steel comparable?
 Is it remotely correct to say:  With the modern technology..folding of steel, type of steel, chemical additives, etc...The steel/sword is better???