I’ll throw my two cents into the pool.
The
Witch-king was invulnerable to
weapons, or at least “all blades perish that pierce” the Witch-king, according to
Strider (
Aragorn) at
Weathertop. This was true of
Éowyn’s
sword, too; but while it seemed of no significant lineage (as were
Glamdring,
Orcrist, and
Andúril), it was effective in “killing” the Witch-king because
Merry first had stabbed him with the Barrow-blade. I don’t suppose the Witch-king was dismissed from
Arda until
the One Ring was undone; in the meantime, he may well have suffered as a
wailing and gibbering spirit in a hole near
Sauron. (The fate
Lúthien foretold for Sauron in
Lay of Leithian Canto IX, lines 2779-2782, in
Lays of Beleriand while
Huan held him pinned by his neck unless he surrendered to Lúthien the keys and words of mastery of his
fortress.)
Glorfindel’s prophetic words that “not by the hand of man will [the Witch-king] fall” seem to me more prescience than prophecy. In this sense, Glorfindel’s observation is more akin to young Aragorn’s insight that
Elrond’s “years of … abiding [in Middle-earth] run short at last, and the choice must soon be laid on your children, to part either with you or with
Middle-earth,” regarding
Arwen in particular (“Tale of Aragorn and Arwen”, Appendix A), than to
Mandos’ fateful Prophecy of the North in which he foretold the ruin of the rebellious
Noldor, the dispossession of the
House of Fëanor, and recurring treachery against and among all the Noldor that continued in rebellion.
The one is foresight, the other foreknowledge, and while the difference may seem but a trifle, I believe it is nevertheless substantial.
Ecthelion mentioned that, “
Tolkien's universe is a fall story.” This, I think, is an essential observation in this thread. Aragorn is great indeed, the greatest of the
Númenóreans since the deaths of
Isildur and his eldest son Elendur, who of all
Elendil’s descendents most resembled his grandfather: Elrond is said to have been struck with the resemblance of Aragorn in mind and body to Elendur, and thus to Elendil himself. (Footnote 26 of “
Disaster of the Gladden Fields”,
Unfinished Tales) But Aragorn was not the equal of either of them: Elendur was 144 years old at the time of his death, Isildur 234; Aragorn lived only to 210 years when weariness overcame him, so that he surrendered his life, but Isildur was still in top fighting form beyond that. The power and effectiveness of the Eldar dwindled from the day the Sun first rose, as well as their numbers and overlordship in Middle-earth.
Melian was accounted the most beautiful
Maia in the garden of
Lórien, the wisest, and the most skilled in songs of enchantment. (“Of
Thingol and Melian”,
Silmarillion) Her daughter Lúthien was the most beautiful of all the Children of
Ilúvatar; her granddaughter Elwing the most beautiful save her foremother; and Arwen, Elwing’s granddaughter, the most beautiful save her foremothers. But each was in turn a little less than Melian, except that Lúthien wove an enchantment in her dark cloak woven from her hair than even her mother had ever made, so powerful that it caused
Morgoth himself to slumber. But Elwing was not Lúthien, nor Arwen Elwing.
Melian was wiser than Thingol;
Galadriel wiser than
Celeborn, accounted wisest of the Elf-kings at the end of
the Third Age; Arwen was wiser (I assert) than Aragorn. Yet though Galadriel was instructed by Melian and patterned herself after her mentor, and Arwen instructed by Galadriel over the long years of the Third Age, each was successively less potent than her predecessor.
Elrond musing upon the banners of
Gil-galad and Elendil allowed, “It recalled to me the glory of the Elder Days and the hosts of Beleriand, so many great princes and captains were assembled. And yet not so many, nor so fair, as when
Thangorodrim was broken…” Then he observed that he had seen “many defeats, and many fruitless victories.” Galadriel told the Company of
the Ring that she and Celeborn “ere the fall of
Nargothrond or
Gondolin … passed over the
mountains, and together through the
ages of the world we have fought the long defeat.”
In
Letter 195, Tolkien wrote,
I am a Christian, and indeed a Roman Catholic, so that I do not expect “history” to be anything but a “long defeat” – though it contains (and in a legend may contain more clearly and movingly) some samples or glimpses of final victory.
Christianity maintains that we cannot win on our own or by our own strength or merits. Middle-earth reflects this belief, never more clearly than when
Frodo claims the One Ring at the Crack of Doom.