Hi Richard, Well I would say its rather worn away & its possible it had something of a belly at one time, which has been damaged then badly ground & now quite smoothed out with its most recent grinding.
So its rather hard to say what it would have been, I am sure it was always fairly slender, but not neccasarily as slim as a sirupate.
Its a wonderfull scabbard though & very auspicios with the sun & moon markings.
Spiral