the suggestion is quite simple.
give mercs, and perhaps slaves, the options of "don't allow anyone armed to get close to you" meaning they'll tell anyone with a gun out to put it away, and shoot them if they get to close.
and "shoot anyone with a weapon" at which point they open fire on anyone with no warning.
and, last but not least. "don't let anyone get past you" mode, which is makes the merc attack anyone who gets to close, thus, if in cities, the merc cannot block doorways still, since he'll die from the guards if anyone trys to block doors with them, but it would allow people to post merc "guards" who are smart enough to defend the controlling characters loot.
this has probally been suggested before, but it'd be a nice touch, at least in my mind.
cheers.
-Ulrek-