could make a variety of things that would be interesting under "alchemy"
smelling salts to revive KO players in pvp
various herbal concoctions etc to reduce "pain" (damage taken) for a short time, or to lessen phlegm drain etc.
poison, slip some poisoned food in your cupboards for raiders to stumble upon or poison your sword etc
gunpowder, fill a barrel up with it and blow up something/someone or flatten land
lots of possibilities that would add depth to gameplay.