the journey of greatest haste and weariness that any among them had known, save he alone,
This passage (after the Paths of the Dead) has always struck me as hinting at Aragorn's life -- the parts for which we have no accounts. It is reminiscent of the comment during the scene at Bree: "I know what hunts you."
We don't know the details of Aragorn's journey into the East (did he encounter the Blue Wizards? did the Wraith become aware of the heir of Isildur? how close did he come to discovering that Sauron was back in Middle Earth?)
Gilraen's fear for her child was very real. How close did the Wraith get to him while he was searching & escorting Gollum?