Heralds play in a chivalrous manner
Heralds play according to the following restrictions:
1. Absolutely no assassinations.
2. No kidnapping for offensive, revenge, or hostage purposes. This means nothing that actually qualifies as 'kidnapping'. There are other possibilities in which the Kidnap menu item must be used, which are legal and honorable purposes, such as taking spies in one's own homeland into custody, or rescue attempts [if that ever gets implemented again]. Those actions are permissible. I think we all know the difference.
3. All prisoners taken will be treated well and not executed, with two exceptions:
A.Heralds may execute common criminals [NPCs] who have found themselves in the Herald's dungeon by a direct criminal attack on them, specifically, kidnappers and assassins who have failed an attempt and gotten captured.
4. National Heralds will, upon taking any Fiefs in combat, immediately transfer captured lands to their King. They are fighting for their Country, not for their personal gain. Such lands will then be at the King's disposal. National Heralds may hold and keep lands given to them voluntarily, by their King or anyone else, but they will not keep personal gains of land made in Combat. This precludes any possibility of Heralds land-grabbing or fighting for personal gain. They are team players. If the King wishes to give them land, he may - there are various reasons this may be done - but they will not take and keep land in Combat. It will be turned over to the players on their team, via the King.
The National Heralds are Knights in their King's service, and may fight honorably for their King in battle, subject to the above restrictions on unchivalrous deeds.
Heralds at Large are restricted to neutrality in the War. They may not take part in active aggression in the French/English war; they may not take French or English fiefs or do battle with armies involved in said War.
They may take part in local disputes outside of the French/English War, also subject to above rules of honorable action [except for #4]. They must not be the aggressor in a dispute, however they may retaliate if they have been attacked, or assist others in settling disputes outside of England or France if they so choose.
The restriction for Sysops are a bit more vague, but are also a lot stricter. The fundamental points to understand about them is that they are neutral and take no active part in the war whatsoever. They may retailiate if attacked, but may not be the aggressor. Neutrality is the key for them.