I see the shade of Denethor, realizing the futility of his own death, watching over his son in this manner, finding the hope he needed to go on now that Faramir was awakened, able with his own soul rekindled with hope to find his way through Namo's halls at the last, even if he cannot recall his own name at the moment. I somehow feel relief that Aragorn was not recognized as Thorongil this time.