stealth character question

When people are back-stabbing with daggers are they duel-wield power attacking or just one handed? as yet i have not managed to instant kill anyone and wondering if i am doing it wrong - my attempts at backstab usually result in the person turning around after i hit them once and spanking me lol.

Try cutting there throat from behind instead of stabbing them in the back. It's far more effective.

Try posting in the right forum and you will get meaningful replies.

I assume you're talking about Skyrim. In that case...

Crouch behind your victim and hold the attack button. If you have the x15 dagger backstab damage you're pretty much guaranteed to kill your opponent on the spot.