"The Cavaliere Ascanio was a cadet of one of the great Venetian houses, pezzi
grossi of the Golden Book."[1]
Pezzi grossi is Italian and translates to something like 'big shots' or 'top dogs' or 'head honchos.' The singular would be un pezzo grosso, reffering to a singular 'big shot.'[2]
[1] Wharton 1901, p. 8
[2] see Collins 2019, Nr. 1