Bold= To not be hesitant or shy. This can be used as a positive trait or a less than positive trait. Bold would mean acting above what an average person might do in the same situation. "The bold man spoke up against the gathering angry crowd and stopped what otherwise might have turned ugly." This would be a positive thing. " The bold man demanded extra food while others were going hungry." A little selfish so not a positive action. Bold does not have to imply courage, "Newton was a bold physicist, always asking, demanding answers." Brave = To be courageous, to put yourself in danger when others might not. Almost always considered a positive trait. Even if the warrior is your enemy, if he is brave you admire that.

Overall, bold is a good quality. It has nuances of gutsy, pro-active, and adventurous as well as morally courageous. On the other hand, it can can imply forward, brazen and rash, even offensive. It really depends on the context and the particular nuance can be subtle. Brave on the other hand is virtually always a good quality. It is pretty much synonymous with courageous.