Let me get this right - the game says it's 93 %, but in reality it seems to be 75 %. So what you would change is the game information. Or is it that you believe the game sometimes "cheat", and let your assasin die even though he shouldn't. And it is the "cheating" you would change?

7 % is a slim change, but not impossible. And sometimes you get unlucky. I've played many civ games where combat odds are given in %, and lost more than once even though I had 99 % change of succes. (Tanks vs. Knights actually, though I find the actual battle situation hard to imagine...)

But I don't know if you've done some serious testing on the matter. I for one would not be overly surprised if the AI actually cheated a little.

/KotR