Mizu is quite obviously clear that Vergil holds himself back significantly when they spar. The dream wherein he fought Dante with everything that he had despite his exhaustion and injuries was likely illuminating enough to that fact. But he certainly sees no reason to toy with the ghosts that mean them harm. Vergil is precise with every stroke of his blade. What he does not catch with Mirage Edge, the summoned blades are quick to pin the ghosts to wherever it is they mean to stand.

"They'll come to regret that."

Although, Vergil cannot help but notice there doesn't seem to be any signs of an end to these ghosts. Their forms dissipate and seemingly wisp away when delivered what would likely constitute a mortal blow were they still alive, but either there's a significant number of spirits here or they just need a few moments to return for more. The answer perhaps doesn't matter entirely too much in the grand scheme of things when it seems the ghosts are not to be discouraged. The bottom line is they cannot fight these ghosts ad infinitum. Mizu will tire first and Vergil will do the same eventually. So, Vergil reverses his grip as he draws Mirage Edge behind him, lowering his stance as he pours his infernal energy into Mirage Edge. His aim is to take a few of the ghosts out, of course, but he also seeks to simply cut their way out of the building if that's what it will take. It seems unlikely to work if Thirteen has had her hand in any of this, but it merits experimenting nonetheless.

Of all the times to not have Yamato...

But he can't dwell on it and he must work with what they have at hand. Once Mirage Edge has crackled into enough life and before the ghosts can close in on him, Vergil swings the blade and releases the energy in the same formation that had once shredded Mizu's side towards the nearest wall.