Yes, yes, the non-beating heart is their main weakness, that and being decapitated and "Dead by Sunrise" and maybe another one that I'm forgetting right now.
But what of the Mages? Are they 100% Human? Human life-Span, human body, human mind? Or, do they have any inheritance from the Father of Magic (still unnamed)? Besides the absolutely dreadful Curse on the female descendants, do they have children? Are any of those children Males? Do they have Magic affinity of any kind, both the males and females descendants?
Why does Ellie have blood tears? How deep goes her connection? Do the other sisters have such a deep connection too? Will they all have blood tears?
I'll refrain to ask about MC specificities, because he IS the story, but I feel that the sisters are fair game at this point.
Peace