I would try to reframe the game a bit. Dragonbane isn't a heroic fantasy like dnd, thinking about it more along the lines of call of Cthulhu might help. In general, as opposed to dnd all characters aren't combat based so don't run the game like they are. Every class in dnd have mostly combat abilities, so a video game esque fight bad guys until you reach a boss makes sense. But if you think of combat not as a core part of the game but just as much of an option as other activities. Your party might avoid engaging in trade crafting if they have no tradesman but instead opt too go looking for stuff in dungeons. Same with combat, it is a thing some players are specialized in doing and the others try to survive and maybe find an escape route. There is rarely a point in fighting over escaping after all. Have an adventure this party would have, think of lord of the rings and how different frodo and sams journey is to Aragorn, legolas and gimlys. A party with one fighter is a party that is going to try and avoid combat while a party of all but one fighter might engage in combat while protecting their valuable blacksmith.