What kind of terminology exactly? Just combat in general? Types of attacks? Or types of formations? Weapons? Orders? Maneuvers? Ranks? Being slightly more specific might help.
Thankfully, most fencing terminology hasn't changed since sword fighting was originally conceived of, so just go on the wikipedia page for fencing and find out what you need to know. Learn what parrying is - and learn the difference between parrying with a blade and parrying with a parrying dagger - and learn what a riposte is. Learn the differences between different kinds of swords so you know which ones are more easily wielded. Go on YouTube and watch fencing videos. There's bound to be some good ones there. As I said, not much has changed in the world of sword fighting since gentlemen started doing it. Really, the only difference is that women do it now too, and it's not used to kill each other.
Also keep in mind that if you're writing in a medieval setting, sword use is somewhat overrated. The most commonly used medieval melee weapon was the spear (thrusting and throwing), as it was economically viable, and easy to make. Only later and more powerful armies would use swords more often. Additionally, if you're going for "duel" battles, then fencing terminology would be best suited. However, in a real life-or-death battlefield situation, such techniques are usually disposed of. Rather than the fancy battle stances and sword moves that one might use in a duel, it's just trying to get the enemy disabled as quick as possible.
Don't be afraid to deviate from the blue book. Is there a word for the smell of the sweat and fear of your enemy as he drops down on you and fights for a short knife dangerously gripped awkwardly in both your hands. His wieght above you, your back on the wet dirt. You chance a hand to let go of the hilt of the boot blade for a split second to grab a rock the size of your fist barely in reach, and bring it across the temple of the young man, someone's son mind you, in a splay of arching blood and the sound of cracked bone. The knife, your knife, falls neatly into the meat of your shoulder scraping bones in white iron pain. So yeah learn what a reposite is, but also realize those things didn't win as many conflicts as pure desperation and base human survival. Also I'd watch movies from every era of historical warfare. If you looking for vivid hand-to-hand then film is a deep well to draw from.
With what weapons? EDIT: And the above poster's advise is excellent. Techniques only cover a minimal amount of what actually goes on in a fight.
A lot of the terms for fighting with swords or other medieval weapons will be generic. Whether you you use swords or fists you're still going to block, lunge, duck, parry etc. Probably more important than the terms for the particular riposte you want to employ is the mechanics of the fight. As one guy lunges forward the other twists aside, blocks or parries the blow then strikes back etc. I know this is going to sound weird - it sounds weird to me too and I've actually done it, but when you're creating a fight scene it often helps to actually act (physically) out the scene. Get a broom stick or what have you, pretend it's a sword and simply see how things move. Then shadow fight against an opponant, and see what works and what doesn't. From memory Robert E Howard used to use this technique. (Only thing I would say - don't let anyone you care about the opinion of, see you. It's sure to make them wonder if you're fully sane!) Oh also a punching bag can be a useful tool, and not just for getting a little agression out and a little fitness in. Stick a face on it, then practice your different blows, uppercuts, jabs, haymakers and so forth. It can give you an appreciation for the noble art. Cheers, Greg.
Never lose sight of your point of view. If your POV is one of the combatants, he won't be "taking it all in." If he does, he's dead. Instead, he'll be focused on parrying that blade, or keeping that gun muzzle pointed away from him, or getting his own blade into any hole in the opponent;s guard. Everything will be quick impressions, not finesse or detail. Keep the sense of urgency and danger by keeping the pace brisk. Terminology can get in the way, so keep it simple.
Hmmm Could you formulate an example (like my post above yours) of a small exchange of blows between characters?
Hi, Gallowglass (who came up with this name?) saw the sword coming for him, a sweeping sideways swipe that threatened to take his head clean off. He ducked to the side, desperate to avoid the strike, and raised his own shield as well. The sword smashed into his shield with a thunderous bang, and the force of the blow almost sent him flying. But instead he held his ground, and his enemy was the one to be staggered. As Ferdinand's (If we've got Gallowglass, why not a Ferdinand?) sword was knocked back by his shield, he saw his chance to strike back. His opponent was off balance and exposed. Striking like a snake he let his own blade dart in to his enemy's exposed thigh and was pleased when he heard him scream. He was even more pleased when he saw the tip of his sword come back covered in Ferdinand's blood. Hope that helps. No parrying, no ripostes no real technical terms at all, and yet I think you can still get a picture for the fight. Cheers, Greg.
I think my favorite method to describe a fight is to use a beat-beat-beat fast-paced style of writing. Gallowglass brought his sword up, then swung. A clash of metal. A sword tip lanced toward his eye, and he parried it with scorn. He riposted, but Ferdinand skipped to one side, letting the blade glance off his shield. Gallowglass kicked out, catching Ferdinand in the shin, and the smaller man yelped and dropped his shield. Without thinking, he slid the shield away from Ferdinand's grasp and attacked. Swipe thrust jab parry dodge swipe block slash block block riposte stab. Ferdinand fell back under the blows. Gallowglass seized the advantage, fighting like a furious dog. A flurry of metal seemed to launch itself at Ferdinand, who was forced to retreat until he felt the wall against his back.
