Windu had the rare ability to perceive shatterpoints -- fault lines in time and space. For example, applying force to the shatterpoint of an object could allow a Jedi to destroy an unbreakable material, and perceiving the shatterpoint of a person or event could give a Jedi information necessary to change the future. When Palpatine became Chancellor, Mace Windu realized that he was the shatterpoint for something important in the future of the Republic, although he did not understand what.
As a fighter, Mace Windu created the seventh form of lightsaber combat: Vaapad, named after a creature whose tentacles moved so fast during its attacks that they could not be counted. Vaapad was a dangerous technique, taking its user close to the dark side in order to channel an opponent's anger and dark side energy back at him.