Inconsistencies in the book

Originally Posted by MatthewM

I can't answer if the sword would have pierced the Witch-King, but my guess would be no, as it was told that no living man could kill the Witch-King, and that Merry's blade of the Westernesse was the only blade that could have affected such damage on the Witch-King, being from the place it was.

The prophecy I think is just a bluff & a sign of overconfidence by the Witch King. Even Sauron, at the peak of his power, was nearly destroyed by the sword.

Sauron had immeasurable power with the Ring, so what does this say about Elendil & Gil-Galad who defeated him in combat? Did they have more power in terms of strength, skill, or sorcery?