Interesting ambiguous morality here, as far as we can see. Akira can basically consume random soul, most of whom must have been Emilio's victims, to resurrect Anthony. Most of those people don't look like power hungry fighters who volunteered to be test subjects in the supersoldier program. They were probably dissidents Emilio and the king hunted down to hide their sins. Like the people in that one village, all slaughtered. Aria says those soul are doomed anyway, but who knows. Aria has her own agency and seems to be suggesting nothing matters as long as Akira is happy.
It would be the best plot development if they were innocent victims, with their souls still possible to be freed to the afterlife, but Akira will consume them nonetheless for his own needs. He would just have to live with the knowledge of having done such a thing. It might actually make his personality better and give him a backbone when he tried to make up for it.