A Queen is the center point of Blood society, even if she's just a figurehead. That little girl could have worn a darker Jewel after her Offering, and she could have been strong enough to rule a Province if she'd been able to find enough males to serve in her court. I suspect the Black Widows had hoped to take her and poison her mind until she was loyal to them before all others. Then, they'd be able to manipulate and control her. Blood males would still want to serve her, and the Black Widows would have been able to control those males through her.

It's been done before. Others will try the same again.