On one hand, she'd managed to toss the komainu away from herself to open her path to the main threat.

On the other, it had instead lunged for Agent Zhao immediately after recovering, what damage she had inflicted far too little to successfully cripple it.

Thankfully, the Chinese Agent had managed to redirect one attack into his new attacker, which meant her pathway to the main threat was still open.

Presumably, the most efficient way to destroy every remaining opponent would be to deal with him rather then take them all out individually. Disabling the central spirit was the best option they had.
 
Why was this spirit using komainu to begin with? If he was a negative presence, how could it even create something in the image of the stone guardians?

It wasn't adding up, especially given the purifying smoke and Agent Zhao's blows hadn't had the expected effects, but there wasn't any time to worry about that now.

If spiritual purification wasn't working, the best possible route was overwhelming him with force.

With most of the enemy dissipated, Arisa could focus, raising Ifrit's enormous blade back over her shoulder and channeling magical energy down her arms, into her fingertips, and up the blade's edge. Flames leaped across the weapon's form, surging across the massive sword and swiftly turning it into a column of fire gripped in both her hands.

Slamming one foot forward, Arisa swung it down, projecting an arc of near-white flame towards the samurai that seared the air as it passed.

Agent Amano's efforts weren't in vain. The naginata was lodged to the floor, and the Agent's first blow struck her in the side. The phantom visibly gritted her teeth, a far more notable response then any prior phantoms had given, before leaping back out of range, hands no longer on her weapon.

As she moved back, she drew its replacement: A rather long-bladed katana gripped in both of her hands, which she immediately swung in a waist-high arc.