刃

1. Origins, structure, and basic meaning

• Structure: 刃 (は) is a noun for the sharpened cutting edge of a knife, blade, or similar tool.
• Basic usage: 包丁の刃を研ぐ makes the cutting edge the object sharpened before slicing vegetables, while 刃に覆いを付ける marks what receives a safety cover after work.

2. Common pitfalls and similar expressions

• Sharpening and covering the edge
  • 刃を研ぐ improves cutting performance, whereas 刃に覆い prevents contact. The noun 刃 does not denote the whole knife or its handle.