[Boromir88]

I'll first start here:

I would appreciate it if you would be kinder in your remarks.

That I do apologize for, it looks harsh and I should have used better wording. From the post before it looked like your argument was that Frodo was stronger (as far as will went) than Aragorn because the Witch-King feared him more than Aragorn. But, I don't think that's what UT was implying because the Witch-King wasn't afraid of Frodo's strength he mustered up. He did figure that Frodo had to be strong enough to get past the Barrow-wights and have the sword of the Westernesse. Also was taken back by Frodo striking at him and that he had called upon Elbereth...but he wasn't afraid of Frodo because he was comparable to Aragorn, or greater than Aragorn. He was afraid of Frodo because of what Frodo possessed (a blade that could kill him) and he used the name of Elbereth. (For which instead of looking in my book I went to a quick reference and missed the rest of it).

I think also it still shows Frodo was terrified of the Witch-King (and this can be supported from the encounter in LOTR)...but the Witch-King was just taken back by Frodo striking at him (and other factors). Frodo acted like a person stuck in a corner...he was still scared out of his boots (err...feet), but he was backed into a situation where he had to lash out...out of fear:

Terror overcame Pippin and Merry, and they threw themselves flat on the ground. Sam shrank to Frodo's side. Frodo was hardly less terrified than his companions; he was quaking as if he was bitter cold, but his terror was swallowed up in a sudden temptation to put on the Ring....
At that moment Frodo threw himself forward on the ground, and he heard himself crying aloud: O Elbereth! Gilthoniel! At the same time he struck at the feet of his enemy.~A Knife in the Dark

I'm not arguing that Pippin had a stronger will than Frodo's, as you show, what Frodo accomplished probably could not have been by anyone else during this time. But I don't see how Sauron would know based upon strength of will that it wasn't Frodo on the other side of the palantir, even had the Witch-King told him the full account. Because:

1. Frodo was still terrified of the Witch-King.
2. I don't think it's reasonable to think that since this encounter and the Witch-King was scared by the events that took place, Sauron would believe any hobbit would be able to contend with his will. Whether it was a hobbit who was able to survive the Barrow-wight and resist the Witch-King or not, neither of them are Sauron. Sauron didn't seem to fear too many things other than someone possibly getting the Ring and challenging him.

Sauron caused him to suffer cruely, so that he felt he was falling to pieces, and I believe he was aware of his effect on the hobbit.

Sauron could probably see Pippin was quite terrified by him, but again Frodo was terrified of the Witch-King. Why would Sauron believe that since this hobbit was scared out of his mind it couldn't have been the Ringbearer then?

My point wasn't about resisting the urge to use the palantir, but to resist the lure towards Barad-dur once the palantir was used.

Why would Frodo be able to resist the pull to Barad-dur? He put on the Ring several times. Frodo had shown that he did not have the will to resist the Ring's pull and the Ring was nearly revealed to Sauron because of Frodo (putting it on to escape Boromir):

'The Ring now has passed beyond my help, or the help of any of the Company that set out from Rivendell. Very nearly it was revealed to the Enemy, but it escaped. I had some part in that..'.~The White Rider

The two powers strove in him. For a moment, perfectly balanced between the piercing points, he writhed, tormented. Suddenly he was aware of himself again. Frodo, neither the Voice nor the Eye: free to choose, and with one remaining instant in which to do so. He took the Ring off his finger.~Breaking of the Fellowship

Knowing this, why would Frodo have the will to resist the pull to Barad-dur (through the Palantir), he didn't have the will to resist the Ring's pull to Sauron. And even if he did, what would make Sauron believe that he could do such a thing?

Sauce pan: In any event, no one asserting that Sauron did not believe Pippin to be the Ringbearer has put forward any convincing explanation as to why Sauron (to Gandalf's mind) would be so obsessed with this Hobbit and why he would want him so urgently, if not only for information.

I think this still remains unadressed. Also, to add, I haven't seen other suggestions as far as what is it that Sauron believed Saruman had (that wasn't his to have) and a Nazgul was coming to get immediately.