The Act of Severance was the symbolic and literal event that marked the creation of Faction Paradox.
When Grandfather Paradox left his imprisonment by the Great Houses, he cut off the arm which had the biodata tattoo binding him to the Houses. This defiance showed that House Paradox was more than a new bloodline, it was political.
The knife that the Grandfather used was preserved in the Stacks, and traces of his blood remained on the blade. Though available, no one ever chose it as their weapon for the sombras que corta ceremony. (PROSE: The Book of the War)