That message which he had received when he got zero potential in the potential test before the old academy got burnt down, at first he thought the message meant that he really didn't have any potential, it was later on that he understood what the message really meant and seeing that same message in his current situation had given him the confidence he needed.
These types of things were built for humans and not Angels, the factors which helped it detect if a human was lying or not wasn't present in an Angel.
General Freelyn tried to hide the shocked expression he had on his face now, Luis had been his prime suspect all this while because George had told him about his little scuffle with him.
It would make sense if he would come back for revenge after getting beaten, he did come back for revenge but George's story was far from what really happened.
