Pure white ceramic handy book ends.
Second hand (ha ha)
Not a suitable present for a priest as they decline to pray being both of the left persuasion.
Underneath each is a bung (or stopper) with a message: HIER VULLEN MET ZAND. Being an erudite band here at cybergrot we know that this is Dutch for "stuff some sand in 'ere." This will make them heavier = Good Idea
Alternatively you could, we suppose fill them with Jenever or some equally potent alcoholic beverage for that secret midnight tipple but we doubt if the bungs (or stoppers) are watertight and we know from experience that books do not like standing in a pool of booze = Bad idea.