Yeah the R63 thing was....weird.
Well we know those horses are the Saddle Arabian ponies now.
The amulet wouldn't be needed by Alicorns as they already have that power. So whoever made it was obviously not one, or maybe a cult worked to death to imbue the amulet with the power of many unicorns, it's red glow is all too similar to Sombra to ignore.
He was just a unicorn, what are the odds he sacrificed crystal ponies to make it, only to lose it when he was defeated? his spirit if not destroyed in the premiere could be out to get it.