Hmmm, to me, the Barrow-Wight and the happenings in the Barrow seem rather mysterious anyway!!
As Tom tells it to the hobbits, the wights came from the outside (" A shadow came out of dark places far away, and the bones were stirred in the mounds") so they cannot be the spirits of the people buried there.
Anyhow, the kings or nobles of Cardolan were not evil people, they were of "the people of Westernesse" and were the owners of the daggers Tom gave to the hobbits (that's the simpler explanation than the one Hookbill gave)
And as for the "houseless fëar" theory : do you mean that's what the barrow-wights were? The fëar can't be the souls of those who are buried there, because those were mortal men. Whose fëar could they be then? Would they have anything to do with Sauron?
And what exactly was the Barrow-wight trying to do with the hobbits, I wonder ? Why take their clothes away and dress them up in white shrouds and jewelry and inspire them (or at least Merry) with the last thoughts of the deceased men of Cardolan ??
Anyhow, if Frodo hadn't been so brave and true to his friends, they would have been doomed - that's for sure! (And since I, too, was annoyed with the "weak" portrayal of Frodo in the movie, I read all these instances where he shows his pluck with satisfaction.)
What I liked best in this chapter are Tom's words about the Dunedain, and the hobbits' vision they evoke. Very beautiful and haunting!. But what it implies becomes only clear when reading the book a second time. This applies to Frodo's prophetic dreams as well, of course!