Not only did they know about honey, but they knew to mix other materials together and get good results. Granted, not all ancient medicine is something I would want to try, but this one gives me hope that we can deal with MRSA and other “superbugs”. I can’t imagine putting that solution in my eye, but I bet it did the trick.
Washing wounds, and treating them with wine, vinegar, honey, and “garlic & onions” would be a good way to prevent infection. In game terms, it would also make it hard to be sneaky around creatures with a good sense of smell. Perhaps good to repel vampires. What other creatures would garlic & onions repel or attract? Garlic would attract the attention of a vampire, and it would send its minions or use long range things, such as spells to deal with the unpleasantness.
Silver is also known to have antibiotic properties, one reason the wealthy used silver tableware. Copper also has antibiotic properties and is why ships were given copper sheeting, to help repel barnacles and other critters that bore into wooden ships and affect either the speed of the ship, its structural integrity, or both
The Roman doctors who treated gladiators and soldiers were very skilled at treating flesh wounds and setting broken bones.
The importance of keeping clean was also known in medieval Europe. The image of the unwashed masses that seems to prevail in textbooks and entertainment media is not accurate.
While the ideas about how the body worked were not accurate, and the reliance on magic and strange concoctions with no modern scientific basis, some of the medicinal knowledge was effective. Some ancient ideas, such as bleeding, do have a very narrow application for a very narrow set of conditions. Leeches are used not for bleeding, but to help improve blood flow in wounds, and the right kind of fly larvae eat necrotic tissue and not healthy tissue. The heads of some kinds of ants after they bite can be used as stitches. There are many strange things that really can and do work, even in the present day.
What kind of weird ideas from the past can be put into play in an RPG?