Since Fourth Shadow and Seth were at that level, when they finally met, he was able to identify his realm and stage of cultivation. Immediately, he informed the whole group of his discoveries, making them change their stance to a more defensive one. At the same time, he initiated a conversation with the enemy.
"Seth... You've betrayed Master Velgor, yet you dare to come back... I don't know if I should call you a brave or a fool. What I know, is that you didn't deserve to be favored by our Master, like you've always been. He had always given you the beast resources and the best opportunities, yet you had to turn your back towards him in the most shameful way, hah!"