There are a few ways to get black armour in OSRS. The best way is to find and talk to a blacksmith. Blacksmiths can make armour for any character, but they are the best at making armour for characters with high Defence. Another way is to find and talk to a blacksmith in the city of Varrock. Blacksmiths can make armour for any character, but they are better at making armour for characters with high Defence. Finally, you can buy black armour from the Armoury in Lumbridge or Draynor Village.