In the contest with the
Palantír Aragorn was the rightful owner. Also the contest took place at a distance, and in a tale which allows the incarnation of great
spirits in a physical and destructible form their power must be far greater when actually physically present. Sauron should be thought of as very terrible.
The form that he took was that of a man of more than human stature, but not gigantic. In his earlier incarnation he was able to veil his power (as
Gandalf did) and could appear as a commanding figure of great strength of body and supremely royal demeanour and countenance.