Rivkin

That's as close to Darcy's writing style as I've seen. Apologies, personally I could never relate to it. It carries an aura of certainty, branding and a signal that the blade being described is superior because kantei is estimation of quality rather than specific features. I am no alien to partisanship in this matter since I own quite a few Tametsugu. The problem at the core is Tametsugu in Edo period oshigata was a rather specific person - a minor Mino smith, very similar but maybe lesser compared to Kinju, with Mino togari and at times specifically Mino jigane with masame in shinogi ji. There are no oshigata of signed Tametsugu blade from his northern pre-Mino times, nor is there is a known signed example. Its Mino period. There was not much reason to attribute blades to him since Kinju and Mino Kanenobu were better recognized and left a number of signed blades. Then little by little these attributions to Tametsugu and Sanekage kept expanding and what was at first minor now became a huge chunk of circa 1330-1380 Soshu. Sanekage remained strictly Uda-ish Norishige, but Tametsugu became almost everything. One of my blades is ex-Norishige and is the only Tametsugu tanto known (mumei, what are the chances). It has too sharp a gunome to be fully comfortable its Norishige or Sanekage and too matsukawa hada to be Kamakura lineage. Is it Tametsugu really? Without any signed period examples its a conjecture. But what other name one could use? There are simply non available or recognized.

Most likely it is shinto, from 1650-1665 judging by sugata - it maybe not 100% kambun but getting there, there is also characteristic widening in the lower half which is also borderline Kambun-like. Wide nie hamon in notare can be in theory Yukimitsu but since it is not even close, shinto, not too many other options. Problem the style was not exclusive to Yasutsugu. Generally the blade can be a good match, but I would check the jigane - it should really stand out even with light completely to the side, and Yasutsugu nie tends to be high quality, nice sandy kinsuji in places. My other suspicion is it can be an early work by the third generation. More precisely is impossible to tell without many high quality photos.

Per se Japanese have little appreciation of old objects conservation in a white men's sense. They see a cultural object as continuing its existence and function until its demise rather than being fixed in a specific state. Its most obvious when looking at the architecture - the "gold pavilion" is one of the most iconic Japanese buildings yet today its very different than it was 100 years and 100 years ago it was very different compared to Muromachi. Wooden architecture, straw elements as part of floor and roof construction means each building is continuously rebuild, maybe couple of beams can survive the entire lifetime, but otherwise when it says "this is 1000 years old" it usually refers to the institution, not exactly this building in exactly this place and in exactly this form. There are relicts where >50% is something very old, but they are rare exceptions. City of Hiraizumi is a great example - in the west this would not happen and if it would, it would not be considered a national historical treasure. In Japan its seen as such. By the same token as long the blade's function and purpose are exactly retained as original, the need is not to preserve the original polish as part of the sword's history, but rather repolish it to fit the contemporary perception of what today is an appropriate appearance for this blade. By the same token Japanese give very little consideration to any second tier (i.e. not properly sealed and written account by government entities) historical provenance associated with a blade; by default they believe such information is faked and therefore unless its confirmed with zero doubt by a modern authority it does not even enter the radar. At the top tier the original Daimyo receipt from Meiji period solicits only shrugs and sniffs, while modern sayagaki of unquestionable authenticity claiming the same provenance is treated as end of discussion argument. For a white person its weird since it is old documents which are needed to confirm the old provenance; for a Japanese its natural since the qualifications of the modern authority are accepted, while old things remain uncertain.

Good pictures of activity taken with dedication to showing the activity would be helpful. Otherwise: 1. EUR 20,000 for o-suriage Yasutsugu-2 is crazy money by about a factor of 5. Effectively its a price of very good signed example. Unfortunately France is its own world in everything scientific and cultural so anything is possible. 2. Shinto can be difficult to kantei and I personally seldom kantei shinto. 3. Broad suguha-notare with nie hotsure is indeed something Yasutsugu well known for. If its second generation the jigane should stand out.

The writing style/nakago is very recent, can be WW2 can be later.

Bizen boshi is photographed by laying down the blade and pointing light from a side (i.e. sword on the left, light on the right), the light source needs to be about 2-10 inches above sword's plane and as far on the side so the boshi does not get blasted by too much light. Then boshi comes out as dark contour.

I would bet 3 to 1 its a high class imitator, but it is ko ichimonji style.

No, its very consistently shows the same thing.

At 1100 you should be good, at least I would buy it if you are selling. It looks like an interesting blade and in 1970s it was simply judged optimistically. There is something weird going on with kissaki, as if it was shortened and there is a question what's happened with hamon there.

This is a complex blade and getting better images might realistically not happen. There is little seen. It needs to be handled in hands. But to give it some prospective: [1] strong multi-layered midare utsuri which reaches high towards shinogi. [2] More or less periodic choji with not much height or width variation in nioi/ko nie [3] The choji is composed from layers of ko nie as if drawn by pencil - very well formed, accented, separate and distinct with inazuma/kinsuji in ko nie. [1] and [2] are very good. This is ko ichimonji style. It really looks like Sadazane where you see kinsuji/inazuma in ko nie. In oshigata this blade would be ko Ichimonji. But... [3] is how first tier imitators of ko Ichimonji worked, for example, in shinshinto. Kiyomaro, Kajihei. The blades they made have much sharper and well outlined hamon structure, compared to more natural, soft and flowing ko-Ichimonji work. Also their utsuri why reaching out to jifu utsuri and reaching to shinogi has very uniform, strong tint, compared to richer appearance of the original. How much money you are in it? Generally I would send this blade to NBTHK for papers. It will fail. Remove the signature. Resubmit. There is a chance you will get a good name.

That's actually looks like a nice blade which I would prefer to look in hand and see what's there. Might have a potential, though the signature is still... ambitious.

Its a Muromachi blade probably before 1540. Deep-ish curvature and pitting on nakago make me worry a bit about Saiha. Otherwise I would consider Uda as a good option.

Everything's possible, but while I've seen koto plenty of fakes, in particular Bizen school ones, with convincing and well executed signatures, I admit to not having experience with a chujosaku shinto gimei where the writing itself would not be problematic at the first glance. But the proper way is ofcourse checking the books.

The signature is well done, so even without look at books I suspect its genuine.

I think in searches the first results are tilted to be the most heavy-traffic sites. It works when you are in newspapers or wikipedia, but otherwise can give some weird results. Danny is a fine man.

Ambitious, at this price level Juyo papers would definitely help matters, otherwise I don't know how hot the interest will be. But that's one of the better if not among the top tier of Muromasa's. Bright, vivid jigane with ji nie and ara nie, strong hamon, absolutely classic Muromasa style.

Japanese tradition tends to attribute the reasoning to something utilitarian, I personally doubt it is often the case, compared to economics/material availability/fashion. Same is very hard and water resistant as is and it survives for many decades without any treatment. I feel that black lacquer was seen as relatively inexpensive methods to improve appearances; for example, the original statement regarding the need to have black lacquered kashira at court did not see it as modest, on the contrary it alluded that people use varied kashira with varied (i.e. natural color) appearance and that detracts from court's decorum. Black lacquered fuchi, kashira and same would be a vast improvement in the time when shakudo fittings were something uncommon. For white same I am not sure of technological process, but I assume it is either boiling or bleaching-like and I doubt any lacquer is involved. There are cultures in which same is polished down a bit to dull the structure of larger grains since holding same without ito can be rather unpleasant; this however is less of a concern in Japan since its same is naturally less "sticky-out".

Nakago photograph, boshi, some macro shots and there is a good chance we can form a decent opinion re what it is. As of now the waki looks like possibly late Muromachi example (deep sori, hirazukuri), but I am also interested in katana - there is some potential here.

Very low resolution, I literally can't see a thing.

I would argue it was blackened in Muromachi, but a formal tachi same was at least often white. In continental tradition per images it is white.

I am probably the worst person to comment on the nomenclature since I have very little interest in it, but there is an inflexion of blade and koshirae classification. It is mounted as wakizashi so as it is, it is wakizashi. The blade itself in shirasaya I would simply call naginata and calling it wakizashi would be unusual. In a sense it is how the blade is supposed to be used as a weapon that affects the proper name. I would expect someone to be more knowledgeable on this, but I've seen a number of tachi where essentially only the final portion was somewhat reworked-shortened being called "ubu". I' suspect that as long as nakago retains the full signature and 95% of its original length it is in koto case can be referred to as ubu.

Internet shows in 99.9% "regular" Soten school stuff which is not the first generation. Books do show first generation's shakudo works and most are not what one would imagine them to be if internet and sword shows are the sole guidance. The school then continued for a considerable time during which it produced more or less the same lineup of items, mostly tsuba, in various quality grades. It was consistently popular, the items were consistently signed as soheishi nyudo soten. They were sold throughout Japan, and very common in certain places. Shakudo was always a more premier and rare kind, but no, this is not the best shakudo Soten I've seen. Its also one of more typical scenes, the really great work tends to be a bit more imaginative. But its definitely in the top 25% of shakudo Soten and top 3% of Soten overall. Nevertheless I personally don't see anything pointing out the first generation. These tsuba were made in significant quantities over very long time. We have no idea who were the great local makers aside from Soten's immedeate circle because they all signed in the same style (i.e. Soten), no dates. Such tsuba maker would be trained by the school from a relatively early age to make tsubas like this - obviously they do tend to look alike as well.

Depends on what kind of authenticity is desired. The founder's work - unlikely. Higher end school's work - probably yes. Sothebies considered circa 1875 which is Meiji, so their belief is its even after-school imitation.

Well, shakudo Soten are rare, especially daisho; this one is single by its still uncommon. Some argue they are seldom of any association with the Soten himself (at least in this style), but they are great examples of the school. In the US at a show the minimum price will likely be 2,000, maybe 3,000 USD. The top is basically determined by whether you find an interested buyer. I once saw an example which sold for 8k, another for 10k. But I would not be sure these prices are repeatable at ease.

Destructive testing. Probably the only serious way to go, but then ofcourse there is nothing to destroy between the end of Kofun and late Heian, so one should rely on Asian data instead. Availability of items for destructive testing is what limiting them - couple of Muromachi pieces, one or two before but plenty of Edo items. I liked Kimura's data but that's pretty much how many pieces he worked with. Kamakura there will be very few opportunities also, probably ko Naminohira is the only thing that can be haid that is not unreasonable pricewise... Maybe some late Kamakura pieces.