that thing is not just a little souvenir - I was certain it would crop up again. And I felt sure it would be used on the G-man once the book suggested that silver was a gholam's weakness. IIRC Jordan broadly suggested that it wasn't the medallions power-canceling ability that caused the burn.
I do love your point about Elayne - it makes terribly good sense for her to be a big alternative/additional target for the creature. They will all be in Caemlyn, so it makes great sense, especially now that the dagger is in her hand. We seriously need Elayne to leave the other Houses alone for a week so she can make like 40 of those, test them, then teach others how to make more.