wire edge
/ˌwʌɪər ˈɛdʒ/Now chiefly North American
noun
1A fine strip of metal produced on the edge of the blade of a knife or cutting tool by grinding or honing, which must be removed before the tool can be used.
2 Figurative and in figurative contexts. Chiefly in to wear (also take) the wire edge off.
Origin
Early 18th century; earliest use found in Abel Boyer (?1667–1729), lexicographer and journalist. From wire + edge.