A pruning hook is an agricultural tool for trimming plants, consisting of a sickle’s blade on a long handle. It’s a period charge, found in the arms of Hegner, 1548 [Vigil Raber’s Armorial of the Arlberg Brotherhood of St. Christopher, fo.401]; Parker, p.540, also cites its use in the arms of Cutcliffe, 1586, but in that case the term may have been simply another name for the sickle.
A related charge, the “pruning knife” (French serpette), has a billhook-like blade; it’s found in the arms of von Görlitz, 1605 [Siebmacher 62]. For related charges, see scythe.
The College of Saint John of Rila bears as a badge: Two pruning knives in saltire argent.
Fedora de Mara bears as a badge: On a bezant invected a pruning hook inverted bendwise sinister sable, surmounted by a peony gules, seeded Or.