In Shatterpoint by stover a novel you read that he walks the razors edge between the light side and the dark side because of his fighting style, Vaapad?

A lot of jedi seem to draw on anger or hatred to destroy their enemies. It seems to me logical to hate injustice and evil, and sometimes to fight it you slip down to your enemies level and use the same tactics because the end justifies the means. At least this is how it works in fiction and in real life for lots of people though i am not speaking from personal experience.

Remember how angry and powerful Obi Wan was when qui gon was cut down by darth maul? He seemed to be drawing on the dark side there to win the duel, kind of how luke goes nuts in return of the jedi.

Anakin goes even further by losing himself to anger over the death of his mother and kills a whole colony of tuskens even women and children. Also out of anger and revenge he cuts off both count dookus hands and when he begs and pleads for mercy beheads him. Then to save padme he kills all his jedi brethren including the children and women, armed and unarmed. Supposedly even the civilians working at the temple who just were in the wrong place at the wrong time.

Also remember Dooku was a jedi and his padawan was Qui Gon. and Dookus master/teacher was Yoda. So not only did Kenobi fail as a teacher training Anakin. Yoda failed as well. Unless the failure was the students alone.

It certainly gives new meaning to Kenobi's speech about anakin " I thought i could instruct him just as well as yoda. i was wrong."

Originally it was Kenobi's pride and hubris for taking on Anakin as a student against the jedi orders wishes, we don't know enough but maybe he broke the rules and was not even supposed to train anyone because he was just a knight and not a master. Now instead of Yoda being the wise one and perfect jedi he is as much a liar as kenobi and a douchebag for allowing Dooku his student to rise to becoming a sith lord.