[davem]

Originally Posted by Kuruharan

There is clear differentiation here between what Tolkien knows and what his characters know. You say that Gandalf implied that Aragorn was capable of wielding the Ring. Tolkien explicitly denied that Aragorn would have been able to do so successfully and so defeat Sauron. Aragorn, for all his high heritage and nobility of character was not on Sauron's level..

Sorry, but I think you're 'doing a Gimli' there:

'Did you say aught to--him? Even Gandalf feared that encounter.' 'You forget to whom you speak,' said Aragorn sternly, and his eyes glinted. 'What did you fear that I should say to him? Did I not openly proclaim my title before the doors of Edoras? Nay, Gimli,' he said in a softer voice, and the grimness left his face, and he looked like one who has laboured in sleepless pain for many nights. 'Nay, my friends, I am the lawful master of the Stone, and I had both the right and the strength to use it, or so I judged. The right cannot be doubted. The strength was enough--barely.' He drew a deep breath. 'It was a bitter struggle, and the weariness is slow to pass. I spoke no word to him, and in the end I wrenched the Stone to my own will. That alone he will find hard to endure. And he beheld me. Yes, Master Gimli, he saw me, but in other guise than you see me here. If that will aid him, then I have done ill. But I do not think so. To know that I lived and walked the earth was a blow to his heart, I deem; for he knew it not till now. The eyes in Orthanc did not see through the armour of Theoden; but Sauron has not forgotten Isildur and the sword of Elendil. Now in the very hour of his great designs the heir of Isildur and the Sword are revealed; for I showed the blade re-forged to him. He is not so mighty yet that he is above fear; nay, doubt ever gnaws him.'

Aragorn has the strength of Will to claim & use the Ring - & Sauron knows that - which is why he fears Aragorn - unless, of course, Aragorn is lying to his friends.