Informed Wisdom is a requirement for purifying items at St. Fermis Church in Metaphor: ReFantazio. As you are able to reach the church early in the game, before you can raise your Royalty Values, this requirement may be somewhat confusing.
If you defeated the infamous dragon battle, and unlocked the impressive loot, it’s very likely that you’re going to want to reach Informed Wisdom as quickly as possible, to purify the dragon’s weapon.
Thankfully, you are able to do this relatively quickly, beginning around the 06/12 Watersday time in-game. This is when you unlock the ability to roam around the city and complete Requests, side events, etc.
Informed Wisdom is basically your Wisdom Royalty Virtue at level 2, and it begins at level 1. So you need to do tasks to increase your Wisdom to level 2. This is very easily done in Grand Trad, on Sunlumeo Street.
Just outside of the Lycaon Magic Assocation, there is a bench. It’s marked on the map by the Wisdom icon. You can rest on this bench to pass time and also earn some Wisdom points. A couple of times should be enough to reach level 2.
At this point in the story, you have nearly 10 days to complete the main objective, which is plenty of time to do all the Requests in the area and sit on the bench a couple of times.