I mean , when i had a lvl 16 assasin , with a multyplier perk , with Power Attack ( and 2 daggers ) all he did was put them up and stab that @#%@$ in a back! No matter how many times i tryed , i still couldnt do it!

What did i do wrong?

You mean Critical Hits or instant kill animations?

Criticals simply do more damage than a regular attack, usually a multiplied amount, and are usually triggered by a perk. And as of right now, instant kill animations might as well be random though some speculate they happen more with power attacks.

As for stealth kill animations, they happen far more often when only using 1 dagger, that is, Ive yet to see any stealth kill animation with 2 daggers and this is my 2nd playthrough with 100 Sneak.

Not sure what you're asking.

Are you sneaking?

One time I was attacking a dragon with a dagger (yeah, I know ), and all of a sudden I had this show of my character jumping on its head and slashing away at it till it died. It was down to about a quarter of its health. THE coolist thing I ever saw! It was great!