Done if by Hand or Hew if by Sword?

[Inziladun]

Originally Posted by CSteefel

Aragorn has had a premonition here that he is the only one who is going to be able to pass through Death, and the sword as the linkage to Elendil (and Isildur) becomes part of this...

The sword was certainly a powerful symbol, but the Dead were not cursed and bound to the world by Elendil, but by Isildur. Narsil was not Isildur's sword at the time of the curse.
The sword was inheirited by Isildur, but more importantly, the authority to release the Dead from the curse was inheirited by Isildur's descendants. I think the latter was what was perceived somehow by the Dead, more than the sword. When asserting his right to pass through, he at no point displays Andúril, or speaks of it. It was his words, and the banner Davem mentioned that proved Aragorn to them. If the sword was what the Dead keyed on, anyone who happened upon it by random finding or theft could have commanded the Dead, couldn't they?