In the middle of Shulk’s desperate death threats, the game interrupts just as you begin another round of fighting Metal Face.
As it turns out, even the Monado cannot injure face-wearing Mechon without their being Toppled. To make things worse, Metal Face, being a huge-sized Mechon, usually will not be Toppled by anything outside of a Chain Attack. Once it’s toppled, though, you can strike it with any sort of damaging attack, just as with a toppled regular Mechon.
The fight resumes pretty much as it was before- the only real difference is that you now know what you need to do to actually injure the massive Mechon. Again, try to keep Shulk and Reyn on opposite sides of the machine- and this time keep ready to switch your central Art selection to the Chain Attack icon. Do your best to dish out the damage- Metal Face can take quite a lot, and you may even find yourself Toppling it with Chain Attacks twice.
At some point, the metallic fiend has had enough damage though, and Shulk, still screaming bloody murder over Fiora’s death, manages to clamber onto the thing’s arm after dodging an attack. Using that limb as his footing, the blond charges at Metal Face’s head, raising the Monado and running said head through just behind the mask, from one side to another. Metal Face begins trying to shake Shulk free, though whether it is just aggravated or genuinely injured by the fresh hole in its cranium isn’t terribly clear. Either way, Shulk tries to wrench the thing’s face off- but isn’t successful.
Metal Face, however, is, presently managing to shake Shulk free and send him tumbling to the cobblestones again. Full of expressionless mechanical wrath, the bloody-clawed Mechon steps forth, rising over Shulk- and then pauses as some sort of signal is sounded by the other Mechon. Looking to the sky briefly, it proceeds to ignore Shulk entirely, instead leaping into the air and doing a rather passable imitation of a Transformer, morphing back into a jet-fightery shape and launching into the sky, leaving Shulk to his rage and Dunban and Reyn to trying to keep the Monado-wielding weaponscrafter in one piece.