on pg 8, should it really be "leotaes"? afaik, the english term is "leotard".
edit, so I don't have to double post:
The note about "retempered swords" is complete bullshit. Though I wouldn't be surprised if the Japanese actually believed this, considering how much bullshit they spew about their swords.
Retempering (heating to 100-400°C) won't make steel brittle. In fact, it'll make it softer. To make it brittle, you'd have to reharden (heat to ~1400°C and quench), then temper at a temperature that's far too low or not at all. Which won't work on laminated blades, since the outer layers have so little carbon that they can't be hardened at all.
Neither process will make the sword look better, as it won't remove scars or burrs, and will decolor the steel (yellow, red or blue depending on the temperature during tempering, or black and red from hardening).
My guess would be that it's actually about regrinding / repolishing. With laminated steel, like the Japanese swords use, there's an extremely hard and brittle layer for the edge, surrounded by soft layers to stop it from breaking. In use, those soft layers become damaged over time, and some idiots will grind them down to smoothen them out. Do that often enough, and there'll only be hard, brittle steel left.
BTW, the Japanese found a "solution" for this by adding a second layer of hard steel to the outside. That's where this "1000 layer nihongo steel" myth comes from. Though the usual constructions only have 5-7 layers (center + 2-3 on each side) and 1-2 on the back. Meanwhile, German and Scandinavian smiths just taught people not to grind the sides and kept using three-layered blades.