Most of them are done by hand.
Welding the blade and the handle.
200 degree high temperature vacuum quenching and cold treatment - 195 degree, greatly increased the hardness and toughness of steel.

[ 6CR Steel ]
- Carbon(C): 0.16 ~ 0.25%
- Chromium(Cr): 12.5 ~13.7%
- Molybdenum(Mo): 0.75%
- Manganese(Mn): 0.5 ~ 0.8%
- Silicon(Si): 0.70 ~ 1%
- Phosphorus(P): 0.035%
- Sulfur(S): 0.030%