"The Knight's Swords
Having equipped our samurai, we must turn to the sword to be used by our knightly combatant. It must be understood there was such a great diversity of knightly swords and armor types. European swords were, in a sense, always specialized rather than generalized designs: there were ones for foot combat, ones for horseback, single and double-hand ones, straight and curved ones, ones for armored and for unarmored fighting, ones for tournaments, ones for civilian duelling, ones ideal just for thrusting or for cutting only, and ones only for training.
A knight's arming sword was typically a one-handed weapon originally (but not always) intended specifically for use with a shield. Their blades are wide and fairly thin and rigid, with chisel-like edges intentionally designed for cutting through maile armor and deep into flesh and bone with a quick, forceful blow. They were light, agile, and stiff, yet very flexible to withstand the trauma of use. They too varied with time from the wider, flatter kinds to those rigid, tapering, sharply pointed and well suited for stabbing both plate and laminated armors. The later wide-based and acutely pointed style of bastard sword was superb at thrusting. So, even though Japanese armor for the most part was made up of the same quality steel as went into their weapons, European blades would likely not encounter anything especially difficult with it that they didn't already face.
Although the Medieval sword and shield combination was fairly common, longer blades useable in two hands were in widespread use from about 1250 to roughly 1600 in Europe. When we talk about Medieval European longswords or war-swords (or even greatswords), we are not dealing with a single uniform style. There were wide, flat blades with parallel edges well suited to powerful cuts. Later, swords specifically designed for facing heavier armor had narrower, much more rigid blades of diamond or hexagonal cross-sections that tapered to hard, sharp points. They were used to whack and bash at armor before stabbing and thrusting into joints and gaps. They were also employed as short spears and even warhammers, yet were still capable of cutting at more lightly armored opponents.
The difference between these two European blade forms is significant and once more underscores the distinction between the manner of using a katana and a straight Medieval European sword. The tapering blade form has a different center of balance and is often a lighter blade. Its point of percussion is located farther down the blade and its fine point is capable of making quick, accurate, and strong thrusts. The wider style can make a somewhat greater variety of strikes and delivers more effective cuts overall. But the later is more agile and easier to guard and parry with. It can also more easily employ its versatile hilt in binding, trapping, and striking. Its proper techniques and style of use is rarely depicted with any accuracy in movies and staged performances. Almost never is the proper historical usage shown with its tighter movements, various thrusts, and infighting with the hilt.
The reach factor also cannot be overlooked. Although a skilled fighter can effectively use a short blade against a long blade or vice versa, and although neither longswords nor katanas had standardized lengths, overall the katana in general is significantly shorter than European two-handed swords and great-swords. A longer two-edged weapon does have advantages -especially if used by a taller man against a smaller with a shorter single-edge weapon. Surprisingly though, the weights between the two weapons are actually very similar and vary within the same degrees.
Surprisingly, the longsword or greatsword is arguably a more complex weapon that the katana. Though there were single-edge versions, it generally has two edges that can be used, as well as a versatile crossguard and pommel permitting a variety of specialized techniques. Another element to consider is that European swords could be used in "half-sword" techniques where the second hand literally grips around the blade itself to wield the weapon in bashing, deflecting, binding, and trapping in all manner of ways that virtually make it a pole-axe or short spear. This was especially effective in fighting against plate armor. We must ponder would this be unusual for the samurai or just very similar to fighting with a short staff? Either way, with its especially sharp edge, a katana is not employed quite like this.
Knightly blades could be excellent swords, but are often denigrated merely as crude hunks of iron while samurai swords are venerated and exalted sometimes to the point of absurdity by collectors and enthusiasts (something the Japanese themselves do not discourage). Bad films and poorly trained martial artists reinforce this myth. The bottom line is that Medieval swords were indeed well-made, light, agile fighting weapons equally capable of delivering dismembering cuts or cleaving deep into body cavities. They were far from the clumsy, heavy things they're often portrayed as in popular media and far, far more than a mere "club with edges." Interestingly, the weight of katanas compared to longswords is very close with each on average being less than 4 pounds."