Sam or Frodo

[William Cloud Hicklin]

Might: Aragorn openly challenged Sauron at the Hornburg, before he ever reached Dunharrow or entered the Paths of the Dead.

Sauron's 'arrogance,' as you say, was a key point Tolkien was making. Sauron cannot imagine what it is to be 'good;' in other words, he cannot imagine that anyone who possessed the Ultimate Weapon would do anything other than he would himself: use it. The idea that anyone would consider actually destroying it was a concept he was incapable of formulating (he also knew nobody *could* destroy it).

The Ring (contrary to the movies) was not some sort of Locator Beacon the moment someone put it on. The near-miss on Amon Hen is somehow to be associated with the peculiar power of that place- and of course at the Sammath Naur Frodo was openly claiming the Ring, at the zenith of its power.