The way I understand how a parry works you are just redirecting the blade not blocking the blow outright. When I took fencing lessons years ago my instructor said you use the six inches or so closest to the guard of your blade for defence. To illustrate this he had each use a modified blade, which was only six inches, to practice parries. I can't recall his name, but he claimed to have trained several sucessful Olympic fencers.

Eh . . . sorry if I sound like a jerk, but I don't buy it.  I fenced collegiate, national championships, and then taught collegiate . . . the last 6" of the blade are no doubt the strongest, but actually training to parry with that 6" is foolish.

Query:  At what point does a professional writer such as Jim cease to take the advice of betas and just go his own route?  I can understand beta readers being a useful tool for a beginning writer, but Jim has over a dozen successful books under his belt.  Isn't it the job of an editor to catch errors in the text?  How much say do betas actually have in the direction a story takes?  Or am I completely misunderstanding their role in the creative process?

It basically goes back to what JB said about them pointing out the things the writer already knows - or at least suspects - are wrong.  Readers point out the writer's blind spots regarding their own works, catch continuity errors (if possible), point out passages or character moments that don't ring true, and reinforce the creeping suspicions the writer already has about his own work, etc.  They aren't there to dictate plot points, rewrite sections, etc.  Personally, there have been VERY few instances in which a reader of my own has pointed something out where my immediate and continued reaction is "Wow, you're just dead wrong."  Usually the feedback immediately makes sense, somewhat more rarely it will make sense after I ruminate on it a few days.

I'd also like to point out something a professor of mine once said in college.  The audience is NEVER WRONG, no matter what they think or say about a piece of art.  Art is a subjective medium, hence, whatever the audience thinks is always correct for that particular person.  Telling a person he/she is wrong about their reaction to art is . . .  well, kind of foolish.  What the creator has to do is weigh each individual's reaction to the art.