While Aisha and Mellie were suppressing Miserius so that Mellie could cast her spell, Daimon and Lucas had already turned the other side of the battlefield into a chaotic mess.
Even in this form Lucas kept doing his best to not be cut by Disaster, but with each clash, more of what used to be his dagger kept being cut apart.
But he also took the those moments contact to counterattack, once the strength behind Daimon's swing had been used to break another part of the dagger, Lucas took impulse and then he hit Daimon with all his might, it's important to mention he has metal affinity.
So he used a boosting spell to cover his skin, and punched Disaster's flat side to avoid being cut by it, that or he directly aimed at Daimon's body.