Leather-Can be in grey chests in the village or be dropped by monsters.
Chain Mail- can be in grey chests or found in the desert.
Plate-can be in grey chests or found in No man's land. Can be dropped by greater skeletons
Ruby- dropped from specters and can be found in the volcanic wasteland.
Golden/Hero's armour-can be collected from a chest after defeating the boss in the volcanic wasteland.