"A curious offshoot is that Harry is now ultimately protected by Riddle's own arrogance. He puts total stock in the prophecy, even though he has only heard a portion of it still. So he believes that he still has to be the one to kill Harry, despite his numerous failed attempts at that. It's a fundamental flaw in Riddle's armoury. So he wont let anyone else kill him ... even that zombie Dumbledore stopped short of taking Harry's life. He wanted to capture him ... and all Harry has to do is let go of his restraint in fighting his old mentor and he should be able to beat him in the future.