Without question at the root of all swordplay is a very simple, hard, and fast rule. Hit them, do not get hit yourself. When swords were impliments of destruction, not being hacked, slashed, stabbed, skewered and so on was the real key to survival. Those who were hacked, slashed, stabbed, skewered, and so on had a tendency to bleed to death, a good parry could keep you alive just long enough to kill your opponent first. Like Martha Stewert says, "Its a good thing."
Now that we are an evolved society who replaced blades with bullets for day to day killing, the martial arts are pretty much religated to sport, exercise, and pay per view TV spectacles. These days at a karate tournament you don't have to deliever a bone crushing blow to your opponent, you simply have to make contact. Fencing has evolved the same way, foil only requires 500 grams of pressure to score, epee only requires 750 grams to score, and with saber it is simply necessary to make contact. The blood sport evolved, from bloody to sporty, and the defense evolved with it. It wasn't that many years ago as sword history goes that two sport fencers were judged on the quality and correctness of their actions even more so than on their actual tip to target contact.
Today just as the touch does not have to be sufficient to kill, the parry doesn't really have as much to do as a defensive action. To quote Mr. Miyagi from the movie The Karate Kid, "Best defense, no be there". This is very true in fencing, the primary defense in fencing today is to make sure that you are not where your opponent's tip is. If you can't be where the tip isn't, then you have no choice left but to move your opponent's tip to where you aren't. Distance is the first defense, parry is the last defense.
Here's the trick. In today's fencing, if you have to parry you don't have to work nearly as hard as you did when the winner of a tournament was the guy who didn't leave in a box. Just as the touch is scored with less than a pound of pressure to indicate a touch, the parry is little more than a sharp lateral movement of the blade allowing the forte of the parrying weapon to contact and move the incomming foible of the attacking one.
A beginner, especially a young one, will always defend as though their life depended on it. Non-fencer children playing swords "fight" by hitting the swords against one another. They aren't trying to hit one another, they are playing swords. A beginning fencer is similar and what you see from the sidelines is the blades pointing at the ceiling, floor, and you-the bystander, seldom if ever at the opponent. (Floor hit.) We train a "proper" parry to move the blade just sufficient to make the incomming point miss your target. As the student gets better we make the parry smaller and more precise until literally all that is left is a sharp "click" sound as the defending blade snaps against the oncomming point and is instantly off in a well practiced reposte.
For the sake of modern right-of-way, the artificial convention of "pretend this thing is really sharp" is delt with by the artificial convention of the modern parry, "I proved I could move my opponent's tip to where I wasn't, and I immediately reposted".
Not that many years ago, you might need to move your shoulder a bit to parry and certainly your elbow. When I started fencing it was necessary to use elbow and wrist to move the incomming blade off target, today defence is in the fingers, specifically the thumb and the index finger. That is how you make the defensive action, that is how you make the audible "click", that is how you get that repost away and on target before the attacker can react. That is how you make touches without being touched upon.
The "click" created by the defensive movement of the blade is all that you really need in Foil and Saber. Epee, where arguably there is no parry at all, since there is no right-of-way there is no need to prove that you defended yourself. Your only concern is hitting your opponent first. Here in the weapon where counter-attack is king and parrys are little more than delaying the inevitable, you must really parry if you intend to use one. Here the parry is all or nothing and you could still give it your all and still get nothing for it. If you choose to parry in Epee, you had better parry like you mean it. Any time you spend not trying to hit them, is nothing more than free time they have to continue to try and hit you. This is why you often hear Epee coaches yelling "Finish!" and never "Parry!".
Any questions?
