This is interesting stuff to me. "[T]hose infernal 7% southpaws" cracks me up. I also believe it's a matter of majority rules, as far as wearing the weapon on the left. I remember from middle school that in art class there were a couple pairs of lefty scissors even. With the bokken, shinai, or katana, however, even though I have learned as a righty, it seems like both hands are quite essential, regardless of the right being in front.
One of the top touring golf professionals in the US, Phil Mickelson, was born a right-hander, but he learned to play lefty from an early age. I think it was his father who taught Phil this because the strong arm for a righty golfer is the left arm. This is evident when watching a righty swing. Because Mickelson's right arm is dominant, when he swings lefty, there's an important advantage for him.
By the way, at the yearly tournament in Doral (near Miami), I was standing next to the "rope sidewalk" that went from the end of one hole (green) to the beginning of the next hole (tee). Mickelson looked at me for a second, then he offered me that smile and nod he often does. It was a fun moment.