Fistuca, fistucæ, pen. prod. fœm. gen. Vitruutus. An instrument to briue piles of woode into the grounde, called a water pile sledge, or a commaunder: also to beate stones in pauing, a tammer.
Lewis and Short: Latin dictionary
fistūca, ae, f., an instrument for ramming down, a rammer, beetle, Caes. B. G. 4, 17, 4; Cato, R. R. 28, 2; Plin. 36, 25, 61, 185.