I should perhaps also add that I hate violence of all kinds, but several of my clients write fighting fantasy and other write thrillers, so I have to know enough to (at the very least) be able to send them off to do more research.
Part 1: Things you can't do in a sword fight.
Actually you can do this, but only if you're desperate. Even with a shield you don't want to block, and a shield is used best to protect you from projectiles and to prevent your adversary from seeing a clear target and, of course, to DEFLECT.
You can do this a little more often than block, but a parry is really a sportsman's move, not a warriors. Literally, a parry is a defensive counter-move that prevents the adversary's gambit from succeeding. It requires a lot of skill and timing, but a warrior skilled enough to defeat his opponent without killing him might do this.
Two things make it impossible to knock your opponents weapon away to one side: one is the main strength behind a thrust. There is a lot of it. A thrust from a wooden walking stick can break your ribs, and when held in a strong grip you can't do anything to push it sideways. Two is inertia. You can't deflect a heavier weapon with a light one, let alone 'bat it away'. If you have a heavier weapon than your opponent, you are more likely to make a combined deflect and attack than first deflect and then attack. See 4.
4. Defend or attack
Okay, what you can't do is either defend or attack. You have to do both at once all of the time. The best sporting fencers, like the best duelists and the best kick-boxers, only ever attack; their defense is a combination of two things: adapting the course of their attack to avoid the adversary's attack and ignoring attacks that they think will do minimal damage.
5. Killing is hard
Actually a novice should ALWAYS attempt to kill his opponent as fast as possible. Only when you severely outclass someone should you attempt to leave them still alive. It is much harder and a really good way to get yourself killed.
Part 2: Making a convincing sword-fight:
Almost everyone's conception of what a swordfight looks like comes from Hollywood, and this is a pity, because what swordfights really look like is gunfights. That's why Leone was inspired by Kurosawa. A real swordfight is over before it started, regardless of the level of skill of the combatants. All their level of skill dictates is how long the fight lasts: very long for novices, less than a second for experts.
Here's the harsh reality: unless you have researched swordfighting in detail or have practiced reconstructive sword fighting (i.e. NOT sporting or stage fighting), DO NOT try to describe what happens in detail. The way to do it is to imagine yourself an ignorant onlooker looking at experts fighting. Many many writers seem to try describing what they think they would attempt to do. Unless you have some dramatic, plot or dare I suggest it symbolic or allegorical reason for describing a sword fight in detail, don't even try.
If you live in the UK, you can go to the Royal Armouries where a gread deal of research into historical techniques has been done, and they can actually show you how a real fight with medieval weapons worked. If you live in Japan there are still a fair number of schools that teach traditional swordsmanship. These things are worth researching! A well described fight can be really absorbing and exciting.
But would you describe a boxing match if you had never boxed and never watched a fight?
That's what many writers attempt when they attempt to describe sword fights.
Part 3: A few words about Bows
++ Bows don't twang. Straight bows do creak when you draw them, just a little, and many of them "whoosh" when you release; a lot depends on the type of arrow. The string itself makes hardly any noise.
++ Crossbows (arbalests) are noisy buggers. Loading is a mechanical clatter, and there is a sudden clonk and the sound stops when the bow is cocked. At that point a quarrel still has to be loaded by hand. When it fires it makes a rattle and a crack more or less at the same time. If it is in poor condition then the springs (bow) will 'buzz' which is caused by the springs vibrating against the stock. This really should not happen. Crossbows have some serious stopping power at less than 100 yards, which is why they are principally a defensive weapon in skirmish and only used offensively on the battlefield. At under 10 yards a heavy crossbow will take your arm clean off, and is very unlikely to miss. What makes them scary is that once cocked you can wait for a target at leisure. You can raise the jeopardy by contrasting the danger of an unskilled opponent at close range who has a short sword with an unskilled opponent at close range who has a cocked and loaded crossbow.
Part 4: Youtube is your friend
Firearms and re-enactment enthusiasts film themselves demonstrating every kind of weapon. This is a good resource for getting an idea of the capabilities and characteristics of historical weapons, as well as providing you with sound. Many videos of the Royal Armouries have been uploaded here.
It all comes back to what you have experienced first hand. I have already remarked that too many fantasy writers rely on what they have read in the books of other fantasy writers. There is no substitute for first-hand research. It is wise to chuse carefully how much detail you will include in a fight scene.