If at any time infiltrators actions can lead to death, it should be mutually risky. If an assassin gains the power to slit your throat in your sleep, the victim should gain the power to parade his head through the town if he fails.
Isn't it already, to some degree? You wound a noble and often become hunted (assuming you escape). You are first banned and then typically executed if caught. To some extent, it's imbalanced
against infiltrators right now; you cannot do any real lasting damage, but you still risk banishment and execution on a regular basis. Sure, the escape chances help quite a lot (I've had infiltrators escape from my dungeons too often... and I was Judge for a month.), but I'd take a drop in escape chances for a shot at lasting effects.
Now, let's go with the idea being presented that there is always a struggle during an assault. Furthermore, going off the text given, we assume the infiltrator is trying to seriously wound the noble. Shouldn't there be a possibility for a failed assault that results in the accidental
death of a noble, be it the infiltrator or the victim? I can't imagine that it would
never happen that a startled opponent trying to defend himself and someone aiming to do serious, not fatal damage accidentally missed the mark and killed someone. It's not like either of them have the finest control in what sounds like it is supposed to be a fracas in the dark.
Also, on the opposite end of the evidence spectrum, infiltrators are often arrested "with a poisoned dagger under his cloak". What's the poison supposed to do? Make the blade look wet?
