expression, i-adjective
Describes a blade or cutting edge that has lost its sharpness. Also used figuratively for things that lack crispness or effectiveness.
この包丁は切れが悪いから、研がないといけない。
This kitchen knife is dull, so I need to sharpen it.
切れが悪い
Cutting paper with blunt scissors is tough.
Similar meaning, but 切れ味が悪い is more common and explicitly refers to the quality of the cut. 切れが悪い is a slightly shorter, more casual variant.
Means 'dull' or 'blunt' as a general adjective, not limited to cutting edges. 切れが悪い is specifically about poor cutting ability.
Compound of 切れ (kire, 'cutting quality') + が (ga, subject marker) + 悪い (warui, 'bad'). The exact historical derivation is uncertain, but the expression is straightforwardly compositional.