Having mastered the art of Akaviri Blade-Dancing, the character has become intimately familiar with using their weapons in perfect harmony, treating them like extensions of his own limbs.
Any Katana wielded in two hands increases their damage value to 1d10. Additionally, if the character is dual wielding with a Katana in one hand and a Wakizashi in the other they may use the two-handed damage value of each respective weapon (Katana 1d8; Wakizashi 1d6) instead of their one-handed damage value.