Your critical strikes from abilities that add combo points have a X% chance to add an additional combo point.
Seal Fate is a 25 point rogue talent located in the 6th tier of the Assassination Tree. It allows critical strikes from all abilities that add combo points a chance to add another combo point.
This ability is sought after mainly for fast Combo Point (CP) generation. It is great when used with Backstab, Ambush, or Mutilate, as all of these moves have a high critical strike rate (through talents). It works well for both PvP and Raiding. Also works well with daggers, seeing as the above three combo point generators use daggers, which can lead to quick burst damage.
Edit
