The odd belief is simply 'one of those things' as far as anyone knows - a bit like men in modern day South Africa believing that the very same thing - sex with a virgin, cures AIDS, or modern day Ugandans who believe a woman can steal your penis through your clothes if she is a witch.

The Haradrim will know very little about elves. They probably see them as almost legendary - perhaps even more than the Rohirrim did - after all the Rohirrim actually had them as neighbours. (Which is also part of the theme in 'Brotherhood'.)

And a society which see females as fairly much 'property' usually believes that what belongs to your wife, or concubine, is rightfully yours - then a small step over the years to this belief with no foundation or logic...

Legolas' reaction is in the next/last chapter. This is a fairly short story, and so winds up with the warriors return - but I think there would certainly be some repercussions on the way that the elven warriors support, or don't support, the men in future.

I may well touch on it in another short story or, in passing, in the longish one I'm doing for the BigBang!, which is the current WIP in the background.

Also jelly beans! Hurrah!