[PK]

My suggestion: Steal from the Forced Entry skill as well.

Professional Skill (Execution): IQ/A

This is the knowledge of how to kill another person quickly and cleanly in a controlled situation. It is of no use if you do not have complete control of your target and access to appropriate equipment (i.e., an executioner's sword as opposed to a normal combat-oriented sword, a chopping block, etc.) Add +1 per die to the damage done to the subject if you know this skill at IQ+1, or +2 per die if you know it at IQ+2 or better. Decapitation takes at least five minutes to set up (use standard rules for reducing or taking more time) and requires a roll against this skill as well as an attack roll against the subject's neck (almost always an All-Out Attack after Evaluating, net modifier +2). If both rolls are successful, the damage is tripled (for a net x6)!

That's fairly generous, but frankly, for executions that don't involve supernatural targets, I'd usually just call it death by fiat anyways. Brings the range of damage from 36-66 up to 48-78 for a skilled executioner, the average of which is enough to easily auto-kill a HT 10 man. A poor damage roll or higher HT target allows for survival rolls, which might necessitate another chop.