Thanks a lot for your careful reply and all the feedback. Indeed, some explanation would have definitely been of much help for the understanding of the mechanics and the enjoyment of the gameplay. Will definitely add that to any future project.
On a brief note, your friendlies fight when their swords collide with the ghosts and will follow them until the ghost is defeated or the friendly dies. Ghosts themselves deal damage by touching the player or the friendlies. The player isn't really supposed to fight as he has very little health, but can deal damage with his staff.
Once again, thanks a lot for tour feedback!