They also resue the effect with Zenos when he kills his farther and the context seems the same, in fact reusing it there makes me feel like their using it to continue the parallel that we're so far and above those around us in strength that at times we can seem monstrous just like Zenos, continuing the "beast" comparison.
Both he and us are a kin to monsters, we simply do good so most see us as heroic, but just like the general world sees Zenos as this horrid unstoppable beast, I'm sure many and more of those we've put down saw what Thordan, this unstoppable "thing" hardly a person.