Victor what are you doing?! Don't give out info!

Oh, this is interesting. Victor seemingly was the one that gave info to Iron Mask about the Zoma (Artificial demon) 6 months before the beginning of the story. Zoma is an experiment made by humans to create a soul from nothing, it usually start very weak and absorb other demons to become stronger. Apparently Zenon wasn't that strong when Victor first saw it and was incomplete.
Victor speculate that it's because it changed it so that it could power up based on the covenant too (and it has 3 of them now). Something happened that allowed Iron Mask to complete it and make it that invincible. The battle against him was a one-sided scripted loss for the player.

Seems like we have a lead at least. Zoma are weak when the new moon is out...so it's time to wait until the next new moon before fighting. Assuming Iron Mask gives us that much time...