http://encyclopaedia-wot.org/items/silver_arrow.html

I completely forgot that the Wonder Girls used this (a totally unique object which is one of two things to be ripped from TaR) for their adam studies. Aw hell, capturing Moggy is prolly way more unique/important, so I can't blame 'em...

Still, Mat feels the medallion after hurting the G-man. His internal monologue says that it isn't cold like when it activates - it's just cool like normal metal is...
I doubt that the burn on the creature happened because two anti-power objects came into contact. Why? Because even in this book series, that's a lot of complication on some minor things...
And if it protected Mat because the Gholam was made by the Power, it would suggest that any power-made objects and shadowspawn would burn when touching Mat/the Medallion. This would mean that stones tossed by the OP are fine, but he/the necklace would damage OP swords, terangreal, and Heartstone. That's weird and complicated. It would make Mat a Typhoid Mary for power-made things, and no way would he let SSpawn lay a finger. So, absurdly complicated... Yeah, I know, Occam's Razor in WoT?

I think(/hope) Mat is preparing for this, since he's a good general and knows the creature has been chasing him across like 4 countries. But the Lightside lives in a world where they don't have our vampire and werewolf myths, so silver as an evil-killer is new for them...

As a result of the arrow's new life, I amend my statement to read that in a thrilling moment of circularity, Birgitte somehow gets a quiver of silver arrows and nails that queen/rapist-murdering jerk. It would have to be new arrows, since I doubt anyone will use Moggy's former choke-chain to attack a Killer Gumby.