Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
shears (n.)
Shears is plural and takes plural verbs, but it can refer either to one or to many such tools: These shears have [all] been sharpened. My shears have been sharpened too. This pair of shears has been sharpened. The singular appears in compounds, as in shear-blade.
