Does that sound confusing? How could an incredible sword not matter? How could a sword, made by a master swordsmith, not matter?
Well, that's what this little article is about.
Let's assume that a katana can split a man from his shoulder to his pelvis. That's pretty devastating. In comparison, my hypothetical longsword can only split a person from his shoulder to his third rib. That's a huge performance difference. The katana clearly wins. So why doesn't this matter? In reality, because whether the victim is split to the navel or merely split to the third rib, that victim is going to die. He's out of the fight. He is equally defeat. As long as two weapons are capable of incapacitating their opponents, the weapons are equally effective.
What about cutting through armor? The longsword can't while the katana can. That may sound mighty impressive, but in order to actually kill someone in armor, you still need to outfight them. Merely holding the best sword in the world does not grant you victory if you don't have the skills to use it. A samurai with a less sword but better skills can still defeat the samurai with the better sword. And on real life battlefields, warriors always chose to fight opponents by gaining their maximum advantage. If they could gang up, they did. If they could wrestle, they did. If they could use arrows, they did. Armor is one element of a fight, but by no means is it the only element to a fight. Cutting through armor is one thing, but cutting through armor while someone inside it is trying to kill you in return is a significantly more difficult challenge. If you don't strike perfectly, your opponent's armor works correctly and stops your weapon.
Now, were all katanas made by master swordsmiths? That's an important question. Katanas were very labor intensive to make. How master master class katanas could a master swordsmith make in a year? In comparison, how many longswords could be made in a year? The math is very clear. Either a limited supply will drive up the cost of a katana, restricting the numbers of your best troops, or you create more average class katanas. Historical Japanese documents refer to bad swords, hastily made, especially in times of strife where new swords were needed quickly. Not all katanas were masterwork katanas. Most would be be average katanas, and some would be below-average.
In comparison, Europe learned to make far cheaper monosteels. They were still expensive, but nowhere as expensive as folded steels. This allowed Europe to develop a wider range of resilient specialty weapons. Were they are awesome as the katana? No. Were they effective? Yes. These weapons were good enough, and as happens so often in technology, good enough beat best.
As they're made of low-grade iron, katanas break. I propose that rather than be reforged, broken katanas would have had their front edges reground and these would have been resold to the poorest classes of soldier. If that sounds like a ninja-to, you'd be right. Poor troops used refurbished weapons. This makes economic sense given the man-hours that went into the katana. You wouldn't just throw away those man-hours. The same phenomena didn't happen in Europe as their monosteels didn't break with equal frequency, and thus never created a similar secondary market.
The problem here isn't the katana, nor their quality, nor your beliefs. The problem here are the real-world conditions. The problems is that the metrics used to measure katana awesomeness don't translate into utility. Much like modern electronics, an object's effectiveness can't be determined only through metrics, and this is why we have reviews. Metrics are just sales promises. Whether those sales promises hold up against reality is an entirely different story.
One more question: what's better, a katana or a longbow? In many ways, that's a nonsense questions. The weapons do two different jobs. They don't directly compare. In the same way, melee weapons also serve different jobs. A katana makes a poor spear. A katana is best used in some sorts of fights, while spears are best used in other sorts of fights. This makes sense when you think about it. So when comparing a weapon, you need to compare the weapon's performance doing its actual job.