The furious glow of his eyes is just a moment, but it's enough -- enough for Jayce to keep his attention focused on Edgard, rather than check in on Viktor and that clatter. Glowing eyes does not automatically equal demon, but they sure don't endear.

Jayce takes a half-step backward. It isn't to concede, but to push forward with a grunt, arms thrust out in the hope of toppling Edgard -- or at least shoving him off balance so he might bodily restrain him. That ought to give Viktor enough time to retreat and request help through the crystals. Even if he suspects Edgard is another demon, he doesn't want to strike him first-- doesn't want to cause bodily harm (if one can do so with bare fists against a demon, anyway) -- on the off-chance that he isn't.