I took it upon myself to examine the depictions given by Vincentio Saviolo, or at least his artist, of the two combatants and their weapons in order that I might discern the length of the weapons though proper by Saviolo for the practice of his art. While Saviolo gives no indication of the length of his weapons in his text, nor gives any particular preference to the length of the weapon desired by him, the depiction of the weapons gives some idea of what these weapons should be like. The following details the short bit of research that I embarked upon in the search for the weapons of Saviolo.
The first question is why? Or more to the point, why bother? To this I answer that having some idea of the length of the weapons is useful due to the effect which the length of a weapon has upon the combat in which it is involved. Clearly a weapon's make-up will have an effect on the combat. Weapons designed for cutting thrust less well, and vice versa. Thus gaining some idea of the length of the weapons in Saviolo will assist in the understanding of his combat, along with the proportion of the weapon to the user, which also has an effect.
What needs to be noted and accepted is that there are some inaccuracies that need to be taken into account. These inaccuracies will become apparent because of the method used and also some of the data collected from external sources. However, even with these factors the results of this examination are useful as it will give at least an approximate answer to the question.
First of all the "average" height of a male of the Renaissance period was researched in order to give some way to transfer the data from the page and into a "real world" setting. By the research performed on this particular subject the average height was established at approximately 5'5" or approximately 165-cm. The second part was to decide on what images to use to gain the data. So four images were selected, the first four given in the manual. Thus there is the depiction of the three single rapier and one from rapier and dagger. With this information gained it was then possible to start examining the images.
All of the images were scaled so that they were all from a common source. These images were then placed upon the screen and measurements taken of the height of the individual, the length of their sword arm, and the length of the weapons. Clearly using a ruler and measuring them off the screen would result in some inaccuracies, and some differences in the measurements given. As a result averages were made across the data. Not to mention any inaccuracies of the artist who produced the images.
The result of the averaging gave some single numbers to generally reflect the height of the individuals depicted, the lengths of their sword arms, and the lengths of their weapons. In order to bring these measurements into the real world, the average height was measured to the "real world" average height. The result of this calculation resulted in an average height in the real world and a multiplication factor to be applied to the average lengths of arms and weapons.
Assuming that the images depict and individual of average height, the swords depicted in the images have a total length of 118-cm or 46", with a blade length of 104-cm or 41". The total dagger length was 43-cm or 17", with a blade length of 30-cm or 12". Further, due to the calculations given, proportions of weapon to height and weapon to arm length are also possible. The sword was approximately twice the length of the arm, measured from shoulder to wrist, and approximately 70% of the height of the person.
I will in no way claim that these are the definitive answers to either weapon length or proportion to the individual as preferred by Saviolo, nor will I claim that these are the lengths of weapons used in his art. However, they are useful as an experiment as they do give us some idea of the length of weapons used in the period. This alone is useful as it allows us to tailor our weapons to a length which is more appropriate to the art which is being performed. Of course averages could have been taken from sword data, however, swords are very personal things and each person will have their preference, thus the variations would have been much wilder. Further investigation is required in this particular matter, however, the information presented is useful in giving a "ball park" and encouraging the use of weapons of an appropriate length for the art being performed.