Did that fighter have to roll a fort save v that coup de grace because he should of. And it would of been well beyond his abilities to make except on a natural roll of 20.
As is the garrote is absolutely brutal. Does it kill things instantly as some here would have it, no but neither does a 2 handed sword and how many hits from that could you take. I find it hard to understand how people feel free to rationalize people surviving crits from lances being wielded by armored knights on a charging horse, survive a raging barbarian maddly swinging a great axe, but then can't accept a garrote not slaughtering everthing in its path just because they got the drop on someone.