Sabers & Curved Swords
To some people, there is simply no reason why a curved sword could possibly be better than a straight sword. For example, a straight sword is easier to thrust with due to the fact that the point is in line with the handle and the center of balance. A straight sword is also easier to parry or block with for essentially the same reasons. So why would anyone want a curved sword, and why have they existed alongside straight swords since the very beginning?
Put simply, straight swords and curved swords are intended for very different purposes: straight swords thrust and chop, while curved swords cut or slice. Here is a great visual and visceral example of the difference. Take a piece of meat (or a mushroom for the vegetarians among you) and place it on your favorite cutting board. Now take your sharpest, non-serrated knife and approach your victim with malicious intent. First, lay the edge against the meat (or mushroom) and attempt to push the blade straight down through. Unless you have a remarkably sharp knife, this has probably not gone very well. Now take the same blade and slide it across the meat (or vegetarian substitute) while pressing down. Unless you have a remarkably dull blade, the results have probably been much better. This is the difference between chopping and slicing, and demonstrates the key difference between straight and curved swords. Because of this difference, curved swords cut flesh better than straight swords, and are also better at defeating leather or fiber based armors; for these armors, you must thrust with a straight sword to have good success, and thrusting with any sword is not as easy as swinging it.
There is another time when a curved sword is better, and that is when fighting from horseback. The advantage comes from the fact that a curved weapon is less likely to "bind up" in an opponent, which is particularly unfortunate when you are riding past your opponent on horseback. In this situation, either you will lose your sword or you will be pulled from your horse, and neither is a good career move. Of course, curved swords are almost useless against metal armor, and are especially poor against chainmail. No weapon is universally useful, which is why we have such a fun variety to choose from.
