[Raynor]

If that's the case, would Sauron think that a hobbit could seriously contend with his own will?

From the report of the witch-king, I would expect that he did.

Pippin seems fairly composed when he gets Sauron's message

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.

he is able to remember what Sauron told him to say

I think it would be fair to say that he was almost brainwashed by Sauron, seeing his reactions afterwards; he repeats his words like a puppet.

he does answer Sauron's question of who he is.

After he was "hurt terribly".

Comparing Aragorn's will and ability to wrestle away control from Sauron through the palantir to Pippin's use of it just isn't fair. Aragorn was 1. the rightful user of the Palantir and 2. the farther away the palantir is from Barad-dur the weaker Sauron's will is.

2. cuts both ways. You are correct about 1., but it seems that Gandalf believes that others too can master the palantir to a certain extant, as referred to above.

I don't think Frodo had such a will. Frodo put on the Ring several times (which seems to me that he didn't have a will of adamant since he couldn't resist the desire to put on the ring).

We should note that, even if Frodo did have his failings concerning the ring, Tolkien noted in letter #192:

Frodo deserved all honour because he spent every drop of his power of will and body, and that was just sufficient to bring him to the destined point, and no further. Few others, possibly no others of his time, would have got so far.

So he very well could have found an urge to look into the palantir had he ever come across one

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.

The Witch-King didn't fear Frodo because he felt intimidated by Frodo's physical traits,

Again, when did I make such an argument? It is twice you are presuming this on my behalf.

Your mis-use of the quote is simply astounding.

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

or any other reason other than the fact that Frodo carried a blade that could cause his end, and indeed did end up causing his end.

I don't think it is right to disregard other referrences in that quote:

But above all the timid and terrified Beared had resisted him, had dared to strike at him with an enchanted swords made by his own enemies long ago for his destruction. Narrowly it had missed him. How he had come by it - save in the barrows of Cardolan. Then he was in some way mightier than the barrow wight; and he called on Elbereth, a name of terror to the nazgul. He was then in league with the High Elves of the Havens.

Simple ownership of the blade wasn't sufficient; a powerful weapon in and of itself, isn't necessarily a deterrent. Frodo proved other qualities that earned the fear of the witch-king.