I've completed the Discerning the Trasmund mission, but the items Lexicon and essence extractor are still considered quest items and are unable to be removed from my inventory. Will be this bug fixed on the next Skyrim update/patch?

Thanks for your help.

Nope and this is not likely to be fixed, so enjoy your quest items. Ohh and don't freak out if you see those 2 items turned red. It's the game being a dike saying "Nope, i'm not going to load the last layer of textures"

As has been said, if a patch does fix it, only a new game would be affected not your existing save game.

On the plus side, quest items, even if the inventory states a weight value, don't count towards your carry weight so it's an annoying stuck item but nothing more.

The lexicon isn't a hard bug, sometimes it does remove but you have to restart the quest from an earlier save point to try it.