Arnold stood in the middle of the deserted grounds. His eyes seemed to be looking at something. Yet there was nothing in front of them. At least nothing that the automatons observing him, could see with their electronic eyes. But in reality, Arnold was trying to make a life-changing decision.
He had been confident about his choice. He might've liked darkness but he secretly despised it as well. Moreover, darkness can not defeat darkness. Since Nicole most probably had shadow affinity choosing shadow affinity for him was pointless.
If he wanted to just increase his strength, then he would've gone for Shadow affinity. But right now, he needed to become powerful in hopes of defeating Nicole but not kill her, and light affinity was where Arnold would like to place his bet right now.