intervening years Nordland has cooled down
I'm just using your post as a jumping off point for my idea, it's not actually related to what you wrote.
[Note, in this scenario, the Enoir no longer make use of trees that require precious metals to act as waystones]. I dunno if this is viable, I'm just throwing out the idea incase something workable can be made from it:
Nordland don't 'deserve' it, sure. It is rewarding Nordland's threat of further demolishing of the Eonir's defences, yes. But putting aside 'right' and ethics and the like, in terms of preventing further encroaching on the forest, something somewhat sustainable:
I wonder how much effort it would take to create a controlled area where trees grow
really quickly, enough for sustainable harvesting that matches or mildly exceeds[1] the amount of wood the current population of Nordland harvests from their forest.
If that area is in the hands of the Eonir, and they are paid by Nordland for the rights to harvest from it, then they have a blatant threat: If Nordland does not self-police against 'rogue' harvesters, we will turn off the enchantment that is growing these trees quickly. If you do not pay rent[1], we will turn off the enchantment.
[If Nordland agrees to police against 'rogue harvesters' then people cutting down the Eonir's defences are unaffiliated with Nordlands's power structures and the Eonir can attack them without Nordland making a fuss]
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If the Eonir are brought to the point of turning off the enchantment, and things go back to the old ways, then trade groups in the empire will loose access to a market, so that should put pressure on Nordland to keep to the 'fast wood growth zone'
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[1] 'paying rent' is to make the Eonir feel better about putting effort towards this enchantment... that is being used to basically
bribe Nordland to not demolish their defences