Curses!

[Gurthang]

Originally Posted by Formendacil

The curse of Morgoth, at least, was broken by death. Nienor and Turin both died, and so were freed. The Doom of the Noldor was breakable by death, and rebirth in Valinor...

But the Curse of Isildur?

The Curse of Isildur held its victims after death, until it had what it wanted.

Yes, I've been wondering about that, too. But the thing I'm wondering is what ability did Isildur have to make such a curse? I mean, certainly he can say anything he wants about then never resting, but what actually makes his curse hold? Surely it was something that did not go with all Men, or else we'd have a lot more curses. Was it some power he possessed by himself? Or was it just that the Valar, or Eru, thought his curse was valid enough to put into fact?