By transforming herself from a prostitute into a revolutionary icon, Chantal achieves some kind of redemption. One of society's great unwashed, a marginalized figure occupying the fringes of that society, Chantal has effected a remarkable change in her identity that has conferred mythical status upon her.
Chantal comes to stand as a symbol for everything the revolution represents. The revolutionaries want to mobilize the masses, to make them see that they're so much better than the establishment would have them believe. And in the figure of Chantal they have a ready-made illustration of the transformative power of revolutionary politics. Just as Chantal has been transformed by her participation in the revolution, so too will the common people.
Chantal's death is, if anything, even more significant than her life. The revolutionary movement now has a martyr it can use to inspire the masses to even greater heights of revolutionary fervor. It's interesting that we never get to find out precisely who shoots Chantal to death. Some literary scholars have suggested that perhaps it was a fellow revolutionary, someone who wanted to turn Chantal into a figure-head capable of galvanizing the people in their epic struggle.
Others have argued that it was the Bishop who was responsible. This is because, it is alleged, he wanted to see Chantal canonized. Certainly, Irma's angry confrontation with the Bishop, in which she accuses him of having the "abominable" idea of having Chantal assassinated, would appear to bear out this interpretation.
In any event, the significance of Chantal's death, like her life, lies in its acting as an example to those who wish to transcend their humble origins and achieve immortal deeds.