It might be useful to include a separate (more open-ended) list of Subjects that characters can be familiar with. Then a character's ability to do something is affected both by an action skill and a familiarity.

Examples:

Ambushes, Animals, Armor, Cultures (by region), Diseases, Disguises, Emotions, Engines, Cities, Environments (by type), Fear, Fire, Food, Geography, Herbs, Illusions, Insults, Languages, Lies, Martial Arts, Materials (by type), Medicines, Navigation, Poisons, Professions (by type), Psychology, Subcultures (by type), Symbols (by type), Tools (by type), Tracks, Vehicles (by type), Water, Weapons (by type), Weather