Rand appears able to tell Darkfriends on sight now. Also, when he comes before the hall, they have a full circle of 13 shielding him, but Egwene and the other Aes Sedai realize that they're no longer a match for him and if he wants to break the shield, there's nothing they can do to stop him.

Remember back in Book 4, when Egwene described her and Elayne as kittens compared to a lion when comparing their power to Rand? That's how Rand's power is to pretty much everyone else at this point. He walks freely into the tower, because he knows there's nothing that the Aes Sedai can do to him.