The “sharpest” knife 刀 in Chinese

刀 dāo is mostly turned into刂 to express different acts with a knife, or other concepts related to knife. So for knife-related meanings, you will see in most cases characters with刂 but not with 刀. 

Tips: characters with刂 are mainly phonetic left-semantic right, such as 肖xiāo +刂 = 削xiāo, 朵duǒ +刂 = 剁duò.