"What the hell happened to him?! Where the hell is he?!"
With his mind stretched thin and the near overwhelming stress of having to keep an entire army at bay by himself, whilst trying to do six different things at once, he wasn't exactly in the right frame of mind to keep his emotions under control. So when he noticed that Corvus had gone missing, he didn't keep his cool all too well.
Fortunately, being blinded by the sudden blast of light helped put a stop to the panic he was currently having and gave some time for his rational mind to take over from his dumb, panicky lizard brain. Whilst his vision was still recovering, every blink making him see countless red spots in front of the blurry world, Seth shifted his focus away from his own vision towards Corvus'.