C17th English Rapier Blades

[urbanspaceman]

Is this what you are talking about? See below:

Incidentally: estocs were very long, rigid, armour-piercing swords carried at the front of the militia.
The 'hollowed' design was one variation which was lighter, and consequently could be longer; square (or diamond shapes) were also used.
The procedure for producing the hollow version was the forerunner to the development of the classic smallsword (and ultimately Brown Bess bayonets) until the secret machine came along.