Timothius:
NO ATTRIBUTES!
The uncharismatic orc who is ugly and unlikable went to etiquette school and learned how to be a diplomat.
Meanwhile, Mary-Sue has high charisma and is totally likable, but is horribly misunderstood, so she doesn't have a diplomacy skill.
Alternatively, you can have attributes, but no one skill is linked to any one attribute. The only problem would be that the generalist who has all 14 across his attributes will never be as skilled at SkillX as the next guy who minmaxes to have a single 20 in an attribute, and then links all his skills to that attribute.
Fate system tied things to who you are more than your actual mechanics. I like this and this is why I keep emphasizing on no attributes. But Fate linked certain skills with certain defenses, which isn't necessary in 6-Knuckle. 6-Knuckle, like City of Heroes, will let you be a nerd tank who used their brains to cause themselves to be harder to take down. Or a pacifist strongman who just wanted to help people, so he became a holy healer.