Well, it shouldn't be that difficult.
I can't do much with scripting, but wouldn't something like this work?
NPC Code:
if (playerchats&&strequals(#c,Non PK Zone)) {
disableweapons;
}
Keep in mind, that I don't even know if this works, seeing as I haven't done real coding in about a year, and as I don't know which commands have been changed, edited, or disabled.