Soon after the attempt to kill her, and long before she addressed the UN on education and was nominated for the Nobel peace prize, Malala Yousafzai's name was being connected with that of Joan of Arc, burned for heresy at the age of 19. Recent appearances, in which Malala has demonstrated undiminished bravery and defiance of the Taliban have made the comparison yet more popular, even in parts of the media that do not normally encourage child warriors. This is Joan of Arc, at her trial: "One life is all we have and we live it as we believe in living it. But to sacrifice what you are and to live without belief, that is a fate more terrible than dying."

And this is Malala, at the UN: "The terrorists thought they would change my aims and stop my ambitions, but nothing changed in my life except this: weakness, fear and hopelessness died. Strength, power and courage were born."

Although it is intended as the highest compliment to Malala's character, the awed invocation of a 15th-century martyr is not, you might think, the most propitious of analogies, or not for a brave, precociously wise teenager whose enemies still want to kill her. As she described to Jon Stewart, last week, how she would, effectively, turn the other cheek to an assassin, the Taliban was reiterating its own threat to destroy her, "whenever we have the chance".

Yousafzai's new book, I am Malala, written with the journalist Christina Lamb, suggests that willed sacrifice is not something from which she, any more than the Taliban, recoils, having been raised, she explains, under the code of Pashtunwali: "The most important value is nang or honour." She was, moreover, named after a revered regional martyr, the 19th-century Malalai of Maiwand. According to Malala, in her moving and illuminating memoir, the early Malalai, the daughter of a shepherd, rallied men fighting the British, with this cry: "Young love! If you do not fall in the battle of Maiwand then, by God, someone is saving you as a symbol of shame." Malalai died aged 18; the British were routed.

"In Malalai," Malala writes, "we Pashtuns have our very own Joan of Arc." Her father used to sing her a song that urges Malalai of Maiwand: "Rise once more to make Pashtuns understand the song of honour." There was also room in her life, before the Taliban almost ended it, for cricket, Justin Bieber and the Twilight films.

After journalists recognised her potential, Malala heard about another young martyr. A BBC correspondent, Abdul Hai Kakar, was looking for a schoolgirl to write a blog about life under the Taliban and Malala, then aged 11, volunteered. "He told me about Anne Frank, a 13-year-old Jewish girl who hid from the Nazis," Malala writes. "It was very sad as in the end the family was betrayed."

Her family did not think she could be a target, as a child. Rather, her father hoped her appearance, at the centre of a US television documentary about the Taliban's closure of girls' schools would be "our megaphone to the outside world". She said she wanted to be a doctor. "But my father told me that 'you have to become a politician'." As well as dictating a BBC blog, she would make numerous television appearances before her whereabouts were discovered and she was shot on the way home from school.

One of her early patrons, a local journalist, Syed Irfan Ashraf, regretted his part in Malala's transformation into an international, but still utterly vulnerable figure. Interviewed for Vanity Fair by Marie Brenner, he described his actions as "criminal" and told her: "I lured in a child of 11." Writing in Pakistan's English language paper, Dawn, after the attempted murder, Ashraf had deplored the "commodification" of Malala, by both politicians and journalists, and "the media's role in dragging bright young people into dirty wars with horrible consequences for the innocent".

Following Malala's survival (with life-changing injuries), her emigration and the international response to her campaign for girls' education, it became possible, after all, to see her almost tragedy as inspirational and even, with her apparent compliance, as her destiny. Although I am sure her book I am Malala is drenched in homesickness for Swat, "the most beautiful place in all the world", many passages recall nothing so much as those lives of the divines, in which everything, however painful, was meant to be. Malala learns, for instance, a hard lesson about stealing; other parables have her moved to pity by children on a rubbish dump or determined, from her earliest years, to become a politician (not a doctor, any more). "I had been spared for a reason," she finishes her book, "to use my life for helping people."

If that is a fairly extreme thing for a teenager to put on the record, Malala's staggering intelligence and fluency tend to prohibit feeble questions, from comparative cowards, about this commitment to sacrifice. Assuming Malala is happy for her father to describe her as not just his own child, but "the daughter of the world", maybe the world is right to accept her, gratefully, as a valuable emblem of female potential. Her every appearance is a reproach to politicians who have tolerated women's subordination as, at best, a cultural inevitability, at worst, as irrelevant. In any case, given the Pashtun horror of losing face, it is difficult to see how Malala could ever change course, as standard adolescents often do (at least according to champions of Ralph Miliband) and pursue fulfilment elsewhere. A book whose lessons could, and perhaps should have formed a triumphant conclusion to this prize-winning period on the public stage, has committed her, in a final rebuke to her enemies, to never leaving it, not even to complete her education in peace. "My father always says that heroism is in the Pashtun DNA," she writes.

So strong is belief in Malala's power to change the world, and the fear of sustaining her enemies, that you would think, from the uninflected enthusiasm for her mission, that it was entirely without risk. True, Edgbaston is safer than Pakistan, the Swat Valley in particular, but the effervescent editorial mood, as the murder threats keep coming in, is in marked contrast, to anyone old enough to remember, to the concern for Salman Rushdie's wellbeing, when he too was condemned to death by foreign Islamists. And Rushdie was an adult. To endorse Malala's lifelong stand against the Taliban, especially now she has added prime ministerial ambition, like Benazir's, to her vocation, may not be, quite, to promote martyrdom, but it suggests that protecting her is still not the overriding priority, any more than it was when the BBC enlisted her poorly anonymised services in Swat.

In fact, if her assassin's hand had not been shaking, the BBC might still be regretting that it ever encouraged an 11-year-old child to align herself with an iconic victim, as opposed to introducing the now 16-year-old GCSE student as a repository for international hopes. It still seems a lot to ask.