My idea regarding the figures & intervals on the blade: since all the examples brought here show numbers from 1 to 120, I think they stand for Venetian military ounces. Venice had a military weight system, different from the civil sustem.
As for using the stiletto for elevation measure - sorry, I don't think so. First, one must use additional tools to the the stiletto and the whole procedure is cumbersome. Second, for elevation taking & aiming there was a very simple yet innovative, precise instrument: the gunner's quadrant.
http://brunelleschi.imss.fi.it/museum/esim.asp?c=100379
http://www.mhs.ox.ac.uk/geometry/fig11m.htm
A very good little book
Artillery Trough the Ages can be found entirely here:
http://www.gutenberg.org/files/20483...-h/20483-h.htm