For once in his life, he can be smart. Odysseus like, "-I'm nobody. -Nobody hurts me."No one we've seen in game would be able to take down the ancients head on, including the MC.
The only plausible solution would be sealing the ancients in again. That's how they were halted in olden times after all.
The barrier is getting the Virgil etc. to believe the level of threat and act accordingly.
I'd be severely disappointed if the MC ends up saving the day with his powers or magic weapons. He wouldn't stand a chance without industrial grade plot amour.