Japanese blades often did not have a tsuba (hand guard)

Nonsense. A tsuba is an integral part of a practical katana. Only decorative or ceremonial long blades occasionally (e.g. shirisaya) lacked them. The tsuba didn't just protect the wielder from an opponent's blade, it also prevented the wielder's hand from sliding onto the blade during thrusts. Fighting with a tsuba-less sword would be folly.

I'm sure Scalzi realizes it's a movie. The article is on AMC, after all. Also, he's written a book about sci-fi movies that includes Episodes IV & V on a list of the most significant SF films of all time. "Ripping apart" the bad science in a science fiction film does not take away from the entertainment aspect of it. In fact, I would argue that it actually adds to the entertainment aspect (at least for those of us who don't turn our brains off when we walk into a theater). My favorite SF film of all time is "Aliens" and that's got some scientific whoppers in it as well. Suspension of disbelief is one thing, but some of the logical contortions fanboi apologists are making in this thread are just pathetic.

...by WHOM...