>>721193920
The Chosen One powers are distinct from the Dark Side. Anakin truly achieved Balance for the first time in his life when he wiped out the Jedi because he truly believed they were evil, the Galaxy was corrupt and he was going to fix it HIS way, he was going to protect his wife, save the Galaxy, and he was finally beyond external limitations and petty politics (even if he he had objectively tricked and deluded by Palpatine, this was genuinely how he thought). But he knew killing the padawans was wrong and that was the beginning of the corruption setting in and his own lack of faith in himself. He tried to compensate by then willfully embracing the Dark Side but while that granted him great power again, it wasn't the same as having complete CONTROL over the Force. And Anakin couldn't master his own emotions anymore, particularly when fighting Obi Wan. He did think Obi Wan had betrayed him, was cheating with Padme and the Jedi were evil buuuuut he didn't REALLY believe it in his heart of hearts. So he could neither activate his Chosen One power or fully embrace the Dark Side to strike Obi Wan down. Anakin was still good deep inside, as only Luke could ever perceive. Of course after the battle, Anakin then actually hated Obi Wan more than anything but also hated himself even more because he knew he had lost because of all those exact reasons and was determined to kill the 'Anakin' in him so he would never be defeated again.