So let me get this straight:
To back the position, that the katana is really one handed one needs to use the Arsenal, to reference a number of quite vague rules and jump to an assumption, that "two-handed" is one-handed, which can be used two-handed.
On the other hand all the opponents of the position have to reference is just the description of the katana using
the most logical and wide-spread definition of "two-handed". That's it.
I'm so with JoeNapalm on this!
BTW, although katana really looks cool and you can admire the design, it's efficiency in combat is hugely overrated (thanks to anime, I guess). My opinion was defined by
this episode of the Deadliest Warrior.