Katana is hardened unevenly: the edge is made hard to stay sharp, the spine is kept softer to bend instead of breaking. As a result, the blade combines sharpness and durability rather than becoming brittle

33 3

6 0

19 0

21 1

11 0

16 4

34 1

15 0

19 1

32 3

25 0

15 1

22 1

15 0

28 0

37 4