There are many videos of sword test-cutting (“tameshigiri”) on youtube and I generally avoid them. A lot of the time, it seems to be someone who got their hands on something katana-shaped and has decided to risk their, and their friends’ lives.
A sword blade must be springy and hard in a great balancing-act. And a blade can sometimes fail. So, what happens when someone is chopping through a rolled up mat, hits it at just slightly the wrong angle, and their over-hardened blade cracks? Well, the end goes helicoptering and, because of the cut it just made, it goes helicoptering with the edge forward. There are other problems; the peg that holds the blade into the handle may be loose, or the handle may be loose, and the impact can shear the peg. Then the entire blade may go helicoptering. This has actually happened and has resulted in tragedy – one iaijutsu master’s blade came out of the handle and killed someone in the audience.
Part of what makes this extra grievous, to me, is the manga and movie presentation of katana as these unstoppable cutting instruments; they are not. They’re really dangerous weapons, not as dangerous as a gun but you don’t want to be around someone swinging a 3 foot razor blade any more than you want to be around someone doing “quick draws” with a revolver (another weapons demonstration technique that has a high casualty rate). If you’re around an expert, it’s highly likely that you’ll be safe but consider this: you’re watching a potentially lethal situation. Sometimes I’ve caught myself thinking “what is wrong with people who watch NASCAR races? do they just want to see cars wreck and maybe a driver get killed?” Motorsports are certainly less dangerous, but all of these things have an underlying potential of turning into something unforgettable or traumatizing. Was what was entertaining the potential lethality of what you were watching?
I’m not offering advice here. Do what you do. It’ll probably be fine.
Also, I’m not criticizing this (obviously highly expert) swordsman. He knows what he’s doing – and this particular cut is harder than most because he’s changing the angle of the blade across its path as he draws it, and if the blade is not perfectly aligned with its path, it’s going to put torque on one side of it, which will drive it in different directions. He’s using one hand, which also means there’s less muscle-memory to register the angle of the blade as it hits the mat. Far be it from me to critique a sword-master’s technique; I’m impressed that he’s willing to do this at all. But watch what happens to the blade when it goes through the mat. I can’t even estimate what tiny fraction of angle his blade was off, but you can see that the blade experiences some stresses that we normally would not observe with the naked eye.
Katana are properly lauded for their sharpness, strength, and flexibility. The differential hardening that gives you a martensite edge on a finer-grained, softer steel back – that’s why this blade did not blow apart. Imagine what could have happened if it had been over-hardened, or it had a weld inside that was not completely clean. What if it was a katana-shaped sword that was made without an understanding of why katanas are capable of doing this sort of thing when they are built correctly?
A small mistake with a weapon can earn you a lifetime of regrets that you can never let go of. As much as I enjoy the attention blade-smithing has gotten thanks to shows like Forged in Fire I do not believe “reality TV” is the right way to expose people to what is a very disciplined discipline. It makes me very unhappy to see a bunch of guys standing around in a TV studio while someone who does not handle a katana very well, destructively tests one. There are other aspects of the reality TV format that bother me, such as their fondness for compressing contestants’ time-frames, deliberately jeopardizing their skill by pulling them out of their comfort-zone; well, it’s not a “comfort-zone” it’s “area of expertise.” In order to add drama to a TV show they are making it harder for the blade-smiths to work safely and confidently. It does not thrill me when I hear someone say “I hardly slept during the 3 days you gave me to make this sword.” It’s all fun and games until someone catches on fire or is hurrying and doesn’t clamp down a blade and helicopters off a finger or two. I think I have more respect for the blade-smiths than the show does, but one should not expect otherwise from reality TV.
The source video, which is really cool and quite beautiful, is here [youtube]