Zoro proved he can trigger Asura at his own command unlike some people lacking manga knowledge were trying to infer.
He doesn't trigger it casually, the enemy must prove meritorious enough for such event to occur. Zoro needs to be pushed enough, this never occurred in that arc, even in the occasion Fuji got his hands on him, Zoro had managed to overcome his slash without relying on it hence it was not triggered.
He doesn't trigger it casually, the enemy must prove meritorious enough for such event to occur. Zoro needs to be pushed enough, this never occurred in that arc, even in the occasion Fuji got his hands on him, Zoro had managed to overcome his slash without relying on it hence it was not triggered.