I found out that among this Fleet of the Holy League who fought the Battle of Lepanto on 7 October 1571. there was a Venetian Galley in the left wing called:
Cavallo Marino (Seahorse) of Candia Antonio De Cavalli
so with a little imagination (why not) this rapier could have belonged to the captain of this ship Antonio de Cavalli.
see.
http://en.wikipedia.org/wiki/Battle_...rder_of_battle
and for Italian.
http://it.wikipedia.org/wiki/Battaglia_di_Lepanto_(ordine_di_battaglia)
The Left Wing
Commanded by Agostino Barbarigo (53 galleys, 2 galleasses)
Venetian Galleasses (2)
Galleass of Ambrogio Bragadin
Galleass of Antonio Bragadin
Venetian Galleys (39)
Capitana Lanterna (flagship lantern) of Venice (L) Agostino Barbarigo, Proveditor General of the Republic
Capitana (flagship) of Venice (L) Marco Querini, Proveditor of the Fleet
Fortuna (Fortune) of Venice Andrea Barbarigo
Tre Mani (Three Hands) of Venice Giorgio Barbarigo
Due Delfini (Two Dolphins) of Candia Francesco Zen
Leone e Fenice (Lion & Phoenix) of Candia Francesco Mengano
Madonna (Milady) of Candia Filippo Polani
Cavallo Marino (Seahorse) of Candia Antonio De Cavalli
Due Leoni (Two Lions) of Candia Nicolς Fradello
Leone (Lion) of Candia Francesco Bonvecchio
Cristo (Christ) of Candia I Andrea Corner
Angelo (Angel) of Candia Giovanni Angelo
Piramide (Pyramid) of Candia Francesco Bono
Cristo Risorto (Risen Christ) of Venice I Simon Guoro
Cristo Risorto (Risen Christ) of Venice II Federico Renier
Cristo (Christ) of Corfu Cristoforo Condocolli
Cristo Risorto (Risen Christ) of Candia I Francesco Zancaruol
Cristo (Christ) of Venice I Bartolomeo Donato
Cristo (Christ) of Candia II Giovanni Corner
Christo Risordo (Risen Christ) of Candia II
Rodi (Rhodes) of Candia Francesco Molini (Konstam gives Kodus)
Sant'Eufemia (St. Euphemia) of Brescia Orazio Fisogni
Bravo (Skillful) of Candia Michele Viramano (Konstam gives Blessed)
Cavallo Marino (Seahorse) of Venice
Cristo (Christ) of Candia III Danielo Calefatti
Braccio (Arm) of Venice Nicolς Lippomano (Konstam gives "of Candia")
Nostra Signora (Our Lady) of Zante Nicolς Mondini
Christo Risordo (Risen Christ) of Candia III Giorgio Calergi
Nostra Signora (Our Lady) of Venice I Marcantonio Pisani
Dio Padre e Santa Trinitΰ (God, Father & Holy Trinity) of Venice Giovanni Marino Contarini
Cristo Risorto (Risen Christ) of Venice III Giovanni Battista Querini
Angelo (Angel) of Venice Onfre Giustiniani
Santa Dorotea (St. Dorothy) of Venice Polo Nani
Ketianana of Rethymno/Retimo Nicolς Avonal
Lion's Head of Istria
Croce (Cross) of Cefalonia Marco Cimera
Vergine Santa (Virgin Saint) of Cefalonia Cristoforo Criffa
Cristo Risorto (Risen Christ) of Veglia Lodovico Cicuta (Konstam gives "of Vegia")
San Nicolς (St. Nicholas) of Cherso Colane Drascio
Some sources include:
Dama a cavallo (Lady on Horseback) of Candia Antonio Eudomeniani
Leone (Lion) of Capodistria Domenico Del Taco