This was one of the first things I learned from my first fencing master. Hold the sword carefully. (One famous Hungarian master my friend studied with had his own spin on this, saying: "hold your sword like you hold your d**k!" 'Nuff said).
We're all taught not to hold the weapon in a deathgrip, and we all take it to heart, but how often do we ever stop to think about why? The reasons are few and very practical:
- Expending too much energy clamping down on the hilt of your sword will tire your hand out too fast.
- Holding too tightly will make it very difficult to move the weapon flexibly and fluidly,
- Concomitant to the above, it actually can make it easier to be disarmed in certain situations.
The masters frequently talk about "Sentiment du fer" the "feeling of the steel," or sometimes just "sensitivity" and make it sound like some magic power, but it's actually very practical and important for a swordsman to develop.
For the attack, the balance of the blade will tell you where the striking part of your sword is. In the case of a thrusting weapon, it tells you where the point of your weapon is, something like the way a gun sight can help a marksman hit the target, IF the sight is lined up properly. If the balance of a sword changes, a swordsman can find his point off by inches or missing the target completely. The fencer's sense of touch lets him put the point right where he wants it.
In the case of a cutting weapon, broadsword, saber, etc., the optimal place on the edge of the sword to hit with for maximum effect is called the "center of percussion." Having a good feel of your weapon lets you know where this is at all times. When actually cutting something, this becomes immediately obvious. Even for a modern sport saberist, who may prefer to hit with the very tip of the sword, the sense of touch still lets you know where the tip of the sword is.
In the case of blade-on-blade exchanges feeling how the opponent's blade makes contact with yours will tell you where to go next. If you engage his blade, you are likely to feel three things:
1) No resistance. This tells you he is unprepared, and you can continue through directly or with a bind.
2) Strong resistance. A lot of tightness tells you the opponent might be nervous, and will almost certainly be responding a tempo behind your lead.
3) Moderate, sensitive resistance. This tells you the opponent is aware of you, too. Offering enough resistance to feel you out (literally). In this case, DON'T close or engage with this opponent without a plan.
Even in the case of a parry,when the opponent attacks and you catch it on your blade, you can feel the quality of his attack and what to do next if you're careful to be aware of what you're feeling. A light, snappy attack may signal an opponent already thinking of his next move and may call for a rapid riposte, while an attack with full, heavy physical commitment will tell you that the opponent may be slower to respond, maybe more likely to be taken in a throw or disarm, if you use grappling in your system.
From the neurological point of view, it's also important to be aware that one's neurology responds faster kinesthetically (physically) when responding to other kinesthetic cues than to visual cues. Which is to say, you tend to respond with your body faster to things that you feel than things you see. A visual cue, like the sight of a sword coming at you, has to be converted in the brain to a series of physical actions to get a response. Th visual-to-kinesthetic conversion only takes a few thousandths of a second, but considering that a straight attack delivered in distance takes about one one hundredth of a second to arrive, those few thousandths make a difference.
It's not uncommon for an advanced fencing student to be given a blindfolded fencing lesson at some point. At one level this may seem very mysterious, and the stuff of kung-fu-movies, but it's actually very practical training for fast physical awareness.
Back-and-forth drills are a great way to develop one's sensitivity, since you're limited to a few, preset actions that you repeat back and forth with a partner. The trick is to repeat the drill a bit longer that you might think is necessary, till the action becomes internalized and you can begin to turn your attention to what you are feeling.
In Tai Chi, they call the development of the touch "listening" and it's a very apt way to put it--listen to what your sword is telling you!