Skill: negotiation - deliberately reaching a mutually beneficial trade or agreement, even in situations of slight power imbalance. Important for rationalists who aim at earning money as an instrumental goal.

(At the 5-second level a key component of this is learning to say "no", being able to overcome one's agreeableness as the default decision.)

(For some reason negotiation in situations of extreme power imbalance seems like it should have a different name, and I don't know what that should be.)