The simplest way to introduce auto attack is via a macro: /autoattack on or off. With it on, your character only auto attacks the default normal attack when Stamina is at 100%. The player may, if they wish, manually speed up the normal attacks if they click the Heavy/Light attack commands.

It's really the best of both worlds. And it's plain and simple. You can turn it off or on to your liking. And you can even speed it up to your liking. Keep in mind, this mechanic still depends on the Stamina bar to function.

-Lonni