Purification of black magic, basically only touched the surface of it. It almost like you wiped something dirty to clean it.
Since there were hundred, if not thousand of variation of black magic, same like magic in general, the dept of the darkness and the fatality of the black magic was also different.
Curse and offensive black magic could be purified. That was what happened to baby Vemion and Iris's babies when she gave birth to them, of course, Abby didn't talk about her babies, since it would open another can of worms, but she gave Iris an example of baby Vemion.
The purification also had different level and it was clear to see Iris had a powerful purification when Abby couldn't cure Vemion's curse, but Iris could do it. Another example was when Iris purified her baby from the black magic when Abby supposed to have her cleaned from it.
