I think a proper bestiary would be nice, and having rolls to examine the creatures you are fighting as well. The later was a feature in DOS2, so I think it would be nice to have here as well.
Maybe give some pre-set class knowledge about creatures as well. Like, I am sure a paladin would know at least something about undead/demons, compared to a rogue.
In terms of learning more after killing - I think that may be a bit too much. Just give all the info after you are done killing, similar to what was in Withcer 3, making a minigame out of it will just take away dev time from other aspects of the game.
