Whilst in Zen Mode, you become completely one with your weapon and focus on nothing but it and your surroundings.
This allows you to better concentrate on combat, as when using fencer mode, your goal is to block an enemies weapon by moving your own weapon into the path the enemies weapon will take, and not by pressing the right blocking key/button as you might be used to.
With certain weapons, a successful block in this way can result in a devastating unleashing of the weapons inner, slumbering powers!
Activating Zen Mode
To activate Zen Mode simply press [L] in game.