Buried City | Necromancers District | Blackbone Guardian

https://www.artstation.com/vakon/store/MrNV/blackbone-guardian-painting-process-walk-through
I found information about elite squad in the necromancers district - Blackbone guardians. They are the best alive (seems like that) fighters in district. Of course, it was not dispensed with magic, after the some rituals their bodies becomes tougth and barely can be damaged. It’s said that because of this rituals, the bones in those bodies are becoming black. Also there is a different version why they are called Blackboned - because of huge, black as night, maces which are reminiscent of the femur. But this is not a simple weapon. If the guard engages in the battle - the weapon is getting activated and its strikes excepting terrible, destructive damage, inflict enormous damage out of decay.
One strike to the ordinary knight, and just handful of rust and that's all that's left. As regard to the guardians, they are not affected by decay. But what happened to them after the city curse? ...