I've been traveling a bit away from home and am checking in on this thread late.
On this laptop, I thought tsuba #1 looked rather realistic and wasn't sure.
The others, as @Manuel Coden has the right of it that there has been a steady stream of these for years and they have been getting better.
Also, @lonely panet cited a good work and the truth that the early ones often (not always) have a nice filo dough layering in the mimi.
Then in the 2nd period some do and some don't. If it is a unique seeming design that strongly represents the philosophy of the school and the iron is correct, you don't always expect the mimi to have those layers. It happens for a variety of reasons.
The kodai ones are often of famous designs and yet lack the full feel of the earlier ones, or their tell tale elements.
Yet the late Edo Norisuke ones are something entirely else. They are like 1st period ones on steroids, but usually under 5mm of thickness.
The Norisuke ones aren't trying to be deceiving, as much as retro-revivial. They really are their own thing, and I've long hoped to find one of the signed Yagyu waveform ones. Either they aren't for sale, or the condition is poor. The good ones are almost as rare as the originals.
I've previously posted a good image of the filo dough mimi from my best 1st period one.
I'd bought it unpapered from a private collection, so YES sometimes real ones do pop up unpapered.
Though I didn't think it needed NBTHK papers, I eventually submitted it for Hozon.
Whether agent error or some confusion in our communication, it ended up going TH. I didn't want the extra expense, but -hey- I'll live.
Still, good earlier period Yagyu and of either provenance or published such that they don't need papers.
The first tsuba is curious. The rest are heavily -Nah... avoid--
Everyone be nice. Yagyu can be a confusing school to know what you are dealing with. I think it took 15 years before I really got into them.