[Jim McDougall]

Good call Victrix (and image by Fernando) of the serpent mark, which is the 'biscione' (=grass snake) of Milan , attributed to makers in that location and apparently in neighboring centers such as Ferrara. Actually the image in Kinman shows this snake as ANDREA FERRARA.
Actually Andrea Ferrara (long believed a fictitious name) worked with his brother at a forge in Belluno or in regions in or near Ferrara. As far as known, only a very few blades with his name exist, but it seems his name became popular as a quality image.

The heraldic symbol of the snake was used by various influential families in these regions since 11th c. It seems most important in the arms of Milan.
Brescia is also situated in this general area and was key in arms making.

In Wallace (James Mann, 1962, p.318, fig. A627) is a rapier from Milan c.1600.
The guard system is similar to this and others into mid 17th c. The globular pommel seems about mid 17th and to correspond in some degree to German examples of rapiers in this period.

The use of Sahagom was of course of the famed earlier Toledo maker which was often applied to blades made in Solingen and spuriously marked. In this case the use of the makers mark on the ricasso (as done in Spain) rather than on blade is notable.
The combining of Spanish name and in this case, Italian mark, further identifies this as a German product and of probably mid 17th c.

To the surprising survival of the wood grip, it is quite possible this was in a context enclosed rather than in outdoor elements. Deep pitting can be the result of long accumulation of dust and absorbing of moisture which of course eventually causes corrosion. Wood does not rot away in the way it would in outdoor elements, at least thats my take.