The "Master" with the "shield" has been revealed to be none other than the human whirlwind, Sy-Klone!
Since Toyfare magazine is the only news outlet who is currently able to reveal what Sy-Klone actually looks like until Mattel officially reveals him on their websites, I'll have to describe him below to the fans who do not have access to the magazine.
So how does Sy-Klone look in the Classics line?
Imagine the Vintage Sy-Klone with his Big Red Ring (the only new element on him as far as we know). The Big Red Ring is large enough to fit around his head above the shoulder level, just like his 200X incarnation. Sy-Klone now has at least one open hand for holding weapons or accessories. As far as we know, his only accessory is his yellow vintage shield. Whether or not he retains his original whirlwind-like spinning action feature, if the chest radar is a lenticular sticker or if the Big Red Ring is removable is currently unknown.
We should learn new information soon!
Thanks to .org member dorrmann for the correction about the 200X Big Red Ring placement!