Jon,
You need to pick a bunch of assumptions to analyze Silver - he fails to give some crucial infromation. There is one case where Silver says explicitly to use the edge to parry (two if you count the back.) There are none where he says to use the flat. The Italian styles he despised use the edge, yet he never objects to this. The evidence suggests fairly forceful direct blocks.
Yet that's the only case you find made explicit in Silver, where he's defending the leg, and he specifically cites "the rule of the backsword". Curiously enough Joseph Sweatnam cites exactly the same rule in 1617.
Carrie the edge of thy rapier upward, and downward, for then thou shalt defend a blow upon the edge of thy rapier, by bearing thy rapier after the rule of the Backe-sword, for this is the strongest and surest carriage of him.
And other rapier masters also emphasize that this is the strongest carriage. So this raises a couple of questions. Why did they feel compelled to justify the use and benefits of the edge parry and why did two Englishmen seperated by 18 years and who took opposite positions on the rapier both cite the "rule of the back-sword"? Why not just cite "the rule of the sword"? To me it implies there never was such a rule that applied to anything other than backswords, and that these and other writers had to make explicit an action that people in the period wouldn't naturally assume was the way to parry a blow.
And of course addressing Silver's move specifically; if you position a sword to hit your leg and stick your own sword out to block it you could very well impact forte to forte, to the point where you should take care not to bang knuckles. Further, unless your opponent has been playing way too much golf, the incoming blow is probably not coming in with the blade level (measured by a line drawn perpendicular to the long axis of the blade from a point on the true edge to the opposite back edge, like an airplane rib), it's from a down-right cut with this line of advance sloping down at around 45 degrees. That would make Silver's move most likely a 45 degree oblique forte-forte impact, not a 90 degree forte-foible edge basher. There are, however, interpretations where he'd be blocking closer to his leg, making at forte-foible impact, but then the blade would flex from the obliquity and relieve the impact's pressure spike.
And as a final comment on his move, he says to cast the blade out with both that particular blow and the back-edge version done to the right. If the opposing blade were being completely stopped then casting out would be rather problematic since continuing the arc of Silver's blade's travel would tend to move the opposing blade down his forte to his hilt, not off the end of his blade as "cast out" somewhat implies. If, however, the incoming blow was an oblique impact from a down-right cut then it's still sliding toward his foible and his continued motion could cast it out. We might have to experiment with the possible interpretations and see what happens in the real world at speed, though.
And just to bat cleanup, Matt said
-Four, if "never get a nick in your edge" was ever a commandment of European swordplay, why so little evidence of it? Why no lines in Von Danzig or Ringeck about "Thus we parry to avoid damaging our sword" or some such?
Von Danzig also fails to warn you not to stick your dagger in your eye, but that doesn't exactly argue for the habit.
