[yinser]

Selection of metal, lamination, presence of a ura (裏), handle material, the ability to make a new handle and attach it to the original metal. A metal chosen for an extreme sharpness may be terribly difficult to sharpen, a metal easy to sharpen may not hold an edge for long.

[yinser]

Most factory chisels are not laminations like hand made Japanese ones are. They are just a single alloy.