Hence why I'd merge all of the non-combat subclass options into it: better trading range, diplomatic work, so on. Still wouldn't be a powerful class, but it'd give more tools to those who aren't active enough for battle but want to contribute. Maybe give them a boost for doing civil or police work?
Something I have thought about for a while is to get rid of subclass and have instead specialisations. The specialisation in general would not add more abilities, but boost the relevant ones. So as you say a courtier would have the non-combat skills and be able to fulfil all those roles, with a small advantage in their area of specialisation.
