In Japan, nami (wave) represents power and resilience. Many samurai used this as a “kamon” or crest, because waves are coming and going which is similar to tactics of Samurai strategy.
Mitsudomoe was created from three joined tomoe, a popular symbol in Japan. Some view the mitsudomoe as representative of the threefold division (Man, Earth, and Sky) at the heart of the Shinto religion. Originally, it was associated with the Shinto war deity Hachiman, and through that was adopted by the samurai as their traditional symbol.
The videos below show the cutting test and the difference in flexibility between the 1st Generation and 2nd Generation. The 2nd Gen is more flexible like a 1060 blade.
More subtle wire brushed hamon which looks like a real hamon.