"On the accusation that he was too easy to defeat: I disagree. He made a good chase of it."
There were several times where Grevious could have used more than one of his four blades to attack Obi-wan after blocking his saber. As cool as 4 lightsabers looked, Grevious (and in that regard, Gillard) did not create a reasonable fighting technique to necessitate having or fully utilizing four blades. Go back and watch what Maul did with two, and how Obi-wan responded, and get back to me.