I found an excerpt from Labyrinth of Evil to be quite interesting:
"Without pausing, Grievous drew two lightsabers from inside his billowing cloak. By the time they were ignited, Mace was already on and all over the cyborg, batting away at the two blades, swinging low at Grievous's artificial legs, thrusting at his skeletal face. The lightsabers thrummed and hissed, meeting one another in bursts of dazzling light. In a corner of Mace's mind he wondered to which Jedi Grievous's blades had belonged. Just as the Force was keeping Mace from being blown from the mag-lev's roof, magnetism of some sort was keeping the general fastened in place. For the cyborg, though, the coherence hindered as much as it helped, whereas Mace never remained in one place for very long. Again and again the three blades joined, in snarling attacks and parries...
As Mace already knew from Ki-Adi-Mundi and Shaak Ti, Grievous was well trained in the Jedi arts. He could recognize the hand of Dooku in the general's training and technique. His strikes were as forceful as any Mace had ever had to counter, and his speed was astonishing. But he didn't know Vaapad - - the technique of dark flirtation in which Mace excelled...
Successful at analyzing Mace's lightsaber style, Grievous alter his stance and posture, along with the angle of his parries, ripostes, and thrusts. The result wasn't Vaapad, but it was close enough, and Mace wasn't interested in prolonging the contest any longer than necessary. Crouching low, he angled the blade downward and slashed, guiding it through the roof of the car, perpendicular to Grievous's stalwart advance...
Slipping into the gap made by Mace's saber, Grievous's left talon lost magnetic purchase on the roof, and the general faltered. Mace came out of his crouch prepared to drive his sword into Grievous's guts, but some last-instant firing of the general's cybersynapses compelled the cyborg's torso through a swift half twist that would have sent Mace's head hurtling into the canyon had the maneuver prevailed...
Instead Mace leapt backward, out of the range of the slicing blades, and Force-pushed outward, just at the instant of Grievous's single misstep. Off the side of the car the general went, twisting and turning as he fell, Mace trying to track the general's contorted plunge, but unsuccessfully. Had he fallen into the canyon? Had he managed to dig his duranium claws into the side of the car or grab hold of the mag-lev rail itself? Mace couldn't take the time to puzzle it out..."
As you can see, this novel painted quite an astonishing picture of Grievous. Made it seem as though he was Mace's near-equal in saber to saber combat - and keep in mind that GG was only using two lightsabers during the above battle.
Just some food for thought. 🙂