PUBLIC MARKS with tags swordsmith & katana

To create an excellent cold weapon, a swordsmith is to achieve two goals: the blade must be sharp but, simultaneously, it should not be brittle. However, these two ends contradict each other. The higher is the carbon content of the steel, the sharper is the sword that is produced from it, but high carbon content also makes the blade fragile. Using ductile steel allows to achieve durability, but the swords made from soft, malleable steel grow blunt very soon.