חָרוֹץ charuts not a straightforward word, it also means "gold" and "diligent" or "sharp". In Is 28:27 (as probably in Is 41:15) the word clearly refers to "threshing" but whether there and in Am 1:3 it means that or whether it simply refers to a "sharp implement" is not clear, I have translated with the less precise "implement" as the cotext makes the reference clear in any case.