Confusion or....
Was Anikan's attack on mace simply out of his confusion? Like he tried telling Mace not to kill him because "It was not the Jedi way" and he didn't understand why the Jedi werebetraying their traditions, and the things that were taught him, or was it to have a chance to learn the life saving tequnique from Sidious, and he couldn't do that with him dead (Duh).
I think it would be so much better if he did it out of confusion so we do have the chance to believe that "there was good in him."