“I am content,” said the monk, “seeing you will have it so. Some water, page; fill, my boy, fill; it is to refresh my liver. Give me some, child, to gargle my throat withal.”
The monk is asking for some water to drink and to help refresh his throat. He may be thirsty and wants some water to quench his thirst. He may also want to gargle his throat with water in order to soothe any soreness. It is possible he is feeling ill and that the water will help him feel better.
https://www.euppublishing.com/doi/full/10.3366/E0968136108000113