How do I interact with the Nordvig Merchant?
Interacting with the Nordvig Merchant (and the Tavern) is only possible after liberating both shires:
When the shires are liberated, you can enter the Nordvig Merchant and spend the coins of the current faction:
The merchant will only accept coins of the currently active faction (corresponding with the current bard's story). Any unspent coins of the current faction will remain on your account, but will not be usable until the bard decides to present the story of that faction again.
The offer of the merchant is also always tailored to the regiments of the current faction. For example, available upgrades will be needed by at least one regiment of the faction. The more chapters you complete on the story map, the more slots become available in the Nordvig Merchant's store.