One of the ways some Native Americans had to control excessive violence and deaths in combat in real life was to provide nonlethal challenges for proving one's prowess.
I think something like this could work very nicely to control griefing or lopsided pvp fights in Xsyon based on the setting and the development of the game I have seen so far. Since it's a game, we can make is a bit darker but still have much the same effect.
Coup would be rewarded for several things.
1) Winning an engagement against a player of higher skill.
2) Hitting a player with equal or higher combat skill, doing damage, then escaping and never taking damage yourself.
3) Sneaking into an enemy tribal area and taking a coup counter from their standard/totem/whatever Xsyon calls the village center.
4) Taking pride from noncombatants outside village limits.
It probably looks pretty odd straight off, especially part four, but please bear with me.
The whole purpose of this idea is to encourage PVP between players of roughly equal skill, or where the aggressor is the lower skill player. It would establish a ranking system for both PVP and Crafting.
Counting Coup would have zero impact during wartime, positively or negatively.
How it would work, roughly?
1) Give Coup to players who perform challenging PVP activity, and take Coup away from those who PVP against relatively weak targets.
2) Coup CANNOT be lost in PVP unless a player starts a fight with a significantly weaker player. Coup would NOT be lost by the stronger player if a weaker player attacks them first.
3) Group combat Coup rules would have to be thought through carefully. Several fairly low skill PVP players should not gain huge amounts of Coup for managing to kill off a single player only moderately higher skilled than they are individually, but if a single player manages to drive off a pack of slightly lower skill players, they should get a significant Coup reward.
4) Allow Coup to be redeemed for items/perks/resources. Coup would be spent like currency at a special shop/NPC. When it is used to buy something, it is transferred to the seller of the item, and you must re-earn it. Your PVP rank would drop if you chose to redeem Coup (you have to prove you aren't getting fat and slow when the other players see you sporting a nice new piece of armor)
5) Allow crafters to provide rewards to supplement the standard rewards offered.
6) Give crafters Pride points for providing rewards for the Coup system, based on how much Coup is used to buy the items.
7) Allow PVP players to take half the current Pride total of a crafter rather than killing them, if the crafter finds their way into an unwanted PVP situation. This pride would add directly to the PVP player's Coup. If a crafter feels that he can win the fight, and chooses to fight, it is handled as a standard Coup engagement.
8) The player provided coup rewards would be bought in an auction style, and the crafter would have zero control of the cost/value of the item. If an item sits for more than a week without being bid on, it is returned to the crafter.
9) The coup paid by the winning bidder is added to the Pride of the crafter.
10) Having a high level of Pride would offer modest bonuses for crafting.
11) Having a high level of Coup would offer modest bonuses for combat.
12 It is possible to have both Pride and Coup.
13) Coup and Pride would recycle but have a sink. The NPC offered Coup rewards would have a static price, and be limited to basic equipment and raw materials, some of which might be high value, but not directly useful in a fight.
So what would this do?
It would encourage PVP. It would encourage crafting. It would encourage Crafters to provide rewards to PVPers, and encourage PVPers to avoid lopsided fights and seek out challenging fights.
Yes, it almost certainly needs tweaking, but from what I'm seeing of the game's flavor, it would fit.