Thing about grays is, depending on the type, they mostly end up white by a certain time in their life. Dappled grays go white. Flea bitten grays don't, but their spots can get more numerous.

I've always seen Bree as more of a Thoroughbred or maybe a Hanoverian. A breed that has the speed and skill level to handle war. Thoroughbreds tend to be a bit flighty, but they also tend to have a ton of personality. Most of the ones I know are good at carrying themselves in that slightly snooty manor just because of the way they are built.

There are also different thoroughbred body styles. Some are more like Secretariat who had a thicker look. Some have that thin racer type look. I could see Bree built more like Secretariat and Hwin the same breed, but a much lighter build as she's a lady's horse and not a war horse.