Ok, I give up. SoE offered on the 12th day promotions from Station Cash, "For one day only the Vault of Serilis will be open!" So, I goggled it, checked Zam & Wiki and Station Cash Marketplace and even asked in the guild, but nothing. Only thing I found was Brell's Vault (aka Vault of Serilis)within the Marketplace which offered a bunch of items from the marketplace that SoE planned on removing. Do I presume it was the same only junk....eerrrr stuff that SoE removed or will be removing from the marketplace? Not that I care since I don't buy anything from Marketplace Station Cash, but was just curious.
You've got it. The Vault of Serilis is where they put stuff when they remove it from the Marketplace. So the 12th day was a chance to get stuff that's been retired from the Marketplace.