The Kal picked up one of the curved swords of the fallen whipmasters and cut Ca'daan's bonds.
It was Ca'daan who cut the Kal's bonds with the dead whipmasters sword. 
mnli hypothesis: It was Ca'daan who cut the Kal's bonds with the dead whipmasters sword.  premise: The Kal picked up one of the curved swords of the fallen whipmasters and cut Ca'daan's bonds.