Final answer:
A jealous stepmother ruined the blood sisters ceremony by her vengeful actions, leading to a loss of sight and damaging the sacred bond shared among them.
Step-by-step explanation:
The blood sisters ceremony was ruined by the vengeance of a jealous step-dame. From the provided text, it appears that this character caused harm through malicious actions, possibly involving a spindle stained with blood. The resulting act inflicted blindness on the step-sons, similarly affecting the blood sisters, which symbolizes a break in their sacred bond and the shattering of their trust and connection. The jealousy and actions of the stepmother are pivotal in the undoing of this ceremonious bond, leaving the blood sisters and step-sons in a state of mutual suffering.