Winsor questline alone would get him a 4, his 5 is from then saying to those who ahd done the winsor questline 'I still remember what you did for me back in stormwind' when he helps kill thel'zan gets him the legendary status
Bolvar represents not only the Might of the Alliance, but also the good that can be found in all of us. I think that's why people like him so much (i'm one of those people). He's good, believes in honor and valor, and he's also pretty awesome in a fight.
Bolvar has always been an awesome character in my book, from his awesome fight with Onyxia's henchman, to the epic confrontation at the Wrath Gate, and (spoiler) his apparent survival and torture at the hands of the Lich King.
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