Thank you!
It seems that it came to me smile

I was at the old topic, there are mostly photos of different times, there are pre-WW2and the 19th century and new.
On the leuku and see the different tips. There are sharper, there are more blunt. I hope it will be interesting.
http://rusknife.com/topic/10021-%D1%81%D0%B0%D0%B0%D0%BC%D1%8B-%D1%81-%D1%81%D0%B0%D0%B0%D0%BC%D0%B0%D0%BC%D0%B8/page-1


I understood about vibration. I think it's not just the thickness, but the overall design of the knife, its shank, the mass and shape of the handle. And more importantly, what part knife you strike.

I see somewhere a detailed analysis of vibrations depending on the form, but only on swords. But now I can not find him frown

I think we would have been helped by guys engaged in historical fencing from AEMMA

http://www.tameshigiri.ca/2014/05/16/why-a-sword-feels-right/

I found!! smile
http://armor.typepad.com/bastardsword/sword_dynamics.pdf
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Si vis pacem, para bellum