No, you didn't bungle what you were trying to say (though you made me laugh, I admit, with that choice of example
).
Glorfindel must have had a good reputation himself if his words were taken in such earnest, and presumably they were also passed on through the generations of Men. What may have been, from him, a strongly worded comment intended to prevent one person from pursuing the WK in folly, may have ended up as what Men (and the WK) took to be prophetic words.
This is all assuming that Glorfindel did not
know what he said to be the truth of course. If he was just using a bit of hyperbole to prevent one man's death, then looking at the results, he may have inadvertently caused the deaths of many (as the WK went on to wreak more carnage when he could have been dealt with sooner had Men not been so afraid of him). But if Glorfindel was speaking words of
truth, then ultimately he did save lives; and also again added to the WK's reputation.