Incendax wrote:
The katana is a versatile weapon capable of being wielded either one handed or two handed as the situation permits. When wielded with one hand you lose control, but gain the versatility of using a offhanded defensive weapon or buckler if you prefer this fighting style. This method was only used against inferior opponents. When wielded with two hands, you gain considerable control over the blade allowing for more complex maneuvers and better reaction time. This method was used against equal or superior opponents.
You can find people today effectively using both methods. In this fantasy world who is to say that you don't consider everyone else inferior. But really, they should have permitted it to be wielded both ways.
You don't only lose control, but grip and power over the Katana. The sword was never meant for one handed use. The blade is too long and thick. I own three, and just from playing with them you need some real arm strength to effectively swing and maneuver the weapon, and even more strength to not lose your grip on the sword when you strike or parry.