I know that you can execute a assassination kill animation by sliding people throat when you crouch directly behind them but the rest are kind of random for me. For example, I used dual wield 1 handed blade and most of the killing animation I get on a human target in direct combat is stabbing them with both of my blade but that's pretty much it, I get some others too from time to time but rarely so can any one give me a heads up? I'm on ps3 if that's matter

There's no way to control the finishers i think. though probably the chance of a finisher is higher when killing with one hand (as in not killing with both weapons) and when not using power attacks?

i love the weaponless face bash then face slam, and the religious beat down watching their lights go out.

It's random

http://www.youtube.com/watch?v=Y5vrsva8c1U
I just found this video and it seem legit but of course, is not 100% however his tip does increase your chances of doing an execution move substantially. Also is seem only possible against weapon wielding enemy, mages who doesn't use weapon and other creatures are random I guess.

Is possibile doing an excute animation when your attack do more damage of the health of the enemy, this is the first thing, the second you must be in front of the enemy and he must be stand up, this is the better way to get an animation, but you must be perfectly in front of enemy, and if they move before you hit is easy you don't get animation.

You can get animation from behind too but with the sames "rules" of when you are in front.