This is pretty awesome. When I first saw your piece and read the "win or die" I immediatly thought of GoT so you did good. The design also looks like a game, sort of wheel of fortune but without all the lights and carnaval stuff but with the unpredictability of the game just like in GoT.
Ah, I see now, the horse head symbol is suppose to represent the Dothraki instead of House Bracken. Well in any case it still seems more symbolic to have the Kingsguard symbol opposite the Night's Watch symbol. But at least it makes more sense now.
Hmm, I know you could've been aiming for visual symmetry but I believe it would be more pertinent to the overall meaning of the whole logo if you replaced the Horse Head symbol (of House Bracken?) with the Kingsguard Crown Symbol (from the HBO tv series) for "Symbolic symmetry" with the Night's Watch crow symbol (Pure white/Pure black; Defenders of the King/Defenders of the Kingdom; both forswear lands, titles and family; consider themselves to be brothers in a family, etc).
The horse head is actually suppose to represent the Dothraki rather than House Braken.
I can see that the Crown from the Kingsguard would be a good choice but as you say the symmetry would have been slightly off. I was also looking for a way to represent the religions of Westeros as well but I think the overall design may have become too cluttered.