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.

[ 9CR Steel ]
- Carbon(C): 0.90 ~ 1.00%
- Chromium(Cr): 17 ~19%
- Molybdenum(Mo): 0.40 ~ 0.70%
- Manganese(Mn): 0.80%
- Silicon(Si): 0.80%
- Phosphorus(P): 0.035%
- Nickel(Ni): 0.60%
- Sulfur(S): 0.030%