i think a cool feature to go with the right mouse button would be free spin, meaning that if you hold m3 the movement you made before starting to press it will go through for up to a certain amount of time. this would make for cool moves like spinning around slicing enemies.
and for the middle mouse button (m3) the player could make a parry move, for example: m3 = a '/' in front of the player, m3+A = a '|' to the left of the player. and the same with 'D' for the right side