In the short story "The Lesser Evil" (the third story in the collection The Last Wish by Andrzej Sapkowski), Geralt becomes involved in a feud between the wizard Stregobor and the princess Renfri. Each of them asks the witcher to help them kill the other, saying it would be 'the lesser evil'. Geralt
refuses to involve himself either way, until towards the end when he realises Renfri and her companions plan to murder innocent townsfolk at the market, and kills them all to stop this.
Towards the beginning of the story, Geralt and Stregobor argue over whether Eltibald's theory of cursed women was true or whether the women such as Renfri were only victimised or righteously vengeful. Stregobor held that they were all monsters with an insatiable urge to kill, but Geralt said this was nonsense. In Renfri's case at least, she had good reason to hate Stregobor, so her desire to kill him doesn't prove that she was indeed a cursed monster. But in the end, who was right in the debate?
Was Renfri, and the others like her, a cursed monster or not?
Geralt's decision to kill her doesn't prove that she was, because the way I read it, the 'greater evil' he was trying to avoid was the murder of the townsfolk, not her existence.
There's also this exchange which I didn't understand:
Geralt retreated and raised his hand, arranging his fingers in the Sign.
Renfri laughed hoarsely. "It doesn't affect me. Only the sword will."
"Renfri," he repeated. "Go. If we cross blades, I- I won't be able-"
"I know," she said, "But I, I can't do anything else. I just can't. We are what we are, you and I."
That might throw some light on my question, if it can be understood and interpreted properly.
Apologies if this is answered in a later story. I've only got into the Witcher series recently, after answering a couple of questions about it on this site.