As an alchemist, get a maximum level Fire Bomb and bow and arrows. Keep running from the Shadow Lord as you are faster than him. When he is near you, walk around him and lay Fire Bombs. They will do about 300 damage each. Drop about six bombs then run away. When you are a good distance away, use your bow and start firing in the general direction of the Shadow Lord. When he is close, repeat the Fire Bomb tactic then run away. Repeat the same trick. Constantly doing this will greatly reduce his HP and he will eventually die.