Not alone

 “Old friend,' said Cadvan, filling another glass for himself
and sniffing its rich smell. 'If we do not trust one another,
we are already defeated.”

I think that among the most vital lessons Fantasy literature has to offer is the value of friendship. Think about it – the protagonist, if indeed there is only one, always relies on her/his friends and allies for support on both a personal and military level. The lesson being that, in the immortals words of Uncle Iroh from Avatar: The Last Airbender, that "there is nothing wrong with letting people who love you help you." In short, friendship and the ability to make friends is more valuable than any magic sword.