The Standard Medium Frame! Shares some design elements with the Hildebrandt (Speaking in terms of production, the Hildebrandt borrows design aspects of the Standard Medium).
The Medium Frame has balanced offense, defense and speed, but isn't ideal for specializing in any particular area like Light or Heavy Frames. This is the average of the average for Medium Frames; slower than a light frame, faster than a heavy frame, etc.
The Standard Bayonet went through about two, three different design phases to reach this point. The first two were pretty ugly. Goes well together with the design though; get a nice guard-like feel from the design.