What is “casehardening”? 

     It’s a metal process to harden the exterior of a weapon while not changing the flexibility of the internal structure. 

     The Japanese use such a method to harden the cutting edge of a Katana to retain a sharp edge while still leaving the sword’s spine flexible to shocks and not be brittle. 

     Why am I posting this here on a woman’s group? It came to my mind this is how a woman is. Hard and dangerous on the exterior yet soft and giving inside. ~ Wade Pennell