Demon Duster

This is can be done if you get the bestiary potion. You can get this potion by finding a mattock in the shrine(use faqs if you can't find it) and then go over to the area where you see a chest which has no entrance(not the one guarded). You should see a crack on the wall. Use the mattock and collect the Bestiary potion. You need to defeat the same monster many times and you have to keep on checking if you got all information from the monster in your notes.