Fu Yu Sheng wanted to crumble like the sand sculptures, he felt like his body was already falling and if not for Fu Chen, who was sleeping in his arms, he really would have fallen to the floor and closed his eyes. There was nothing else he could do about this situation, he was tired and felt as if energy has been sucked thoroughly from his body.
He wasn't far off the mark either, when he used the talisman to ward off the evil, a majority of his Yang energy was leeched off from his body making him feel lethargic and weak. This was how Song Yan has drawn the talismans, she knew that for warding off the demonic entity more effectively Fu Yu Sheng's Yang energy could come off as very useful which was why she made those talismans according to her husband's physique.
