I remember seeing this a year ago on the migration period/early medieval blades. My only qualm (as a conservator) is that they're polishing down complete blades heavily to study the folding traces, which seems a bit unnecessary when there are plenty of fragments out there that could give the same result (which for example the aforementioned italian metallographic analysis used...for pretty much the same result).
The "reading of the blade" involves polishing the upper levels of the blade down to get at the forge-welding patterns in the blade (themselves a result of the process of forging ingots together before welding these ingots together - pattern welding is mostly a decorative process, after all). The forge-welding patterns
can be used to indicate the smith/tradition/workshop in Japan (it is an empirical-based tradition) if the blade is of the better quality ones. The "lesser" (and vast majority of produced, if not survived ones) japanese blades are not that easy, and foreign blades are of course entirely outside their expertice.
It is good that they've finally analyses a late roman-era blade and thus conclusively proven that the romans (in that case...four blades are hardly much of a stastitical sample) used the same procedure as their "barbarian" neighbours...anything else would have been very odd, really - as is apparent to pretty much anyone who knows anything about swordsmithing. There's been a pretty persistent myth out there claiming that roman blades were not welded together (exactly how they would have been produced then is still a mystery - even after the advent of the blast furnace iron rods were faggoted together to create iron bars - itself a forge welding process).
What I would like to know is if there is any signs of martensite structure steel in the blade edges. If this is the case, the last "special" japanese sword-forging technique will not be special to them anymore. The tatara is essentially just a differentl-built bloomery iron smelting overn, the pattern welding process ("thousands of layers" :-) ) ) thought spesific to Japan forty years ago now has been shown (several times) to be more general process (which had survived in the west in knife-making traditions unbeknowst to academics), case-hardening and temperance methods generally were also similar...the only thing the rest of the world is missing is the final cooling process for martensite.
A note about wootz and damascene steel. Wootz steel was (due to its cost and forging difficulties with the wootz ingots) primarily used as cutting-edge material rather than composing the whole of the blade. Thus a blade can have its softer shock-absorbing portions forge-welded and its edge made from wootz steel. Damascene steel, it seems to the current (two, and vigorously arguing over details) research teams on the subject, to have often incorporated wootz ingots. The modern term "damascening" is often applied to certain forge-welding patterns, which is probably nonsense from a historical perspective.