The gem was laying there on the ground, and Eiro's focus was pulled toward it whether he wanted it to happen or not. It was like his head was forced into its direction, and there was nothing he could do about it.
Eiro pushed his foot under it and kicked it upward, as he wasn't really able to easily pick it up right now. In the end, he caught it by just making a small 'nest' with his arms in front of his chest. The impact hurt a quite bit as his arms were broken right now, but in the end, he could get through it.
Quickly the demon made his way over toward the others so that he could get some healing. The guy that threw that boulder into his direction most likely just left right away after the Lady disappeared. Or that's what Eiro thought at first, but then he turned around as another boulder was coming. This time he wouldn't be able to block it, but he couldn't just dodge either... the children were right behind him.