Right, while Seht is very strong for sure, the most dangerous thing about him is his deviousness and cunning. It's what kept him alive for centuries while stronger mages and demons than himself were undone. The first lesson he ever learned was not to tamper with forces he couldn't control. That said, he plays up the image of an arrogant wizard-god to scare off fools and lead the foolhardy to their doom. As Sun Tzu said, appear weak where you are strong, and strong where you are weak.