Palladium Weapon, Castle, & Armor Compendiums
In Palladium’s early years, they released an interesting variety of RPG supplements. My favorites are the Weapon, Castle, & Armor Compendium series. Each book tackles a particular region and time. They are inexpensive, and contain great background material by Matthew Balent, with line drawings, floorplans, and sketches by Michael Gustovich, Michael Kucharski, Kevin Siembieda, Mary Walsh, and others. There have been numerous editions over the years.