Oh, I meant if you signed a peace treaty to end a war. I'm not sure if the code distinguishes between the conditions. I hadn't really thought about it.
The time I actually implemented it I think I made it only apply if you made a peace treaty while you had the highest score, or it might have been if your score was higher than the civ with whom you made peace. Barbarians would understand if you had to make peace in order to survive, but sparing "civilizations" that are weaker than you just isn't right.
I was also thinking that I'd probably add an AV-only repeatable ritual with high AC requirements that let you make peace with the barbs (meaning the Horsemen and Avatar attack your enemies instead of you), but with some dark consequences. This ritual would only work while at war, and just like a barb civ you'd loose the treaty for showing too much mercy. This doesn't really make the trait stronger, but if you do have war declared on you (or if you declare war on them) then you'd have a way to get the peace back. I might make it give the other civs that build it gain the Barb trait and its tech penalty too.