Remove the "to far away from home" mechanic. Or make the mercenary setting a lot stronger.
I'm fond of this. I think it would be helpful to the game if you could feasibly pick fights with distant realms. Looting parties that could be sustained abroad. Not indefinitely, but something that allows players the ability for a trade-off distance with effeciency.
Making mercenaries cost more but be entirely immune from 'too far away from home" mechanic would be my change.