Communication. Cooperation. Coordination.
Concealed behind his Alchemic Stars of Transcendent Purity, Wei Wuyin's Celestial Eyes of Spiritual Divinity noticed those three things throughout this exchange. Not only was he testing the limits of his base form's physical strength, speed of his reflexes, bodily durability, and spiritual aspects, but he was testing the limits of his opponents' concocted tactics, executed effectiveness, level of reliance on, and the properties of their Heavenly Treasures and Mystic Powers as Sages.
The Cultivation Art that Su Mei had received from the eight False Doors that sought to infect the soul had been delivered to his Second Mind and assiduously studied, and as he observed the night-imperceptible communication of spiritual aura and intent, Wei Wuyin confirmed that the Cultivation Art, just as the rumors assumed, suggested that the eight Sages had an unimaginably close relationship to each other.