Inscriptable Platinum Blades... where to find 'em?

Actually, until now I was quite sure that Platinum Blades are a Factions-ONLY weapon skin.
However, I just saw 2 auctions for inscriptable Platinum Blades.

So what happened? Do inscriptable weapons drop in Factions as well (now)? Have Platinum Blades been moved to the Core tier? Do they drop in DoA?

The new Hall of Heroes chest, most likely.