Hickory: Some quest items are not properly 'declassified' and that's the way it's *always* been. Also, quest items weigh nothing, so they can't be "taking up most of your carry space". Some quest items are left there intentionally because you still need them, such as the Eye of Nehaleni. Regardless, every item resides within the same inventory. The different categories are just virtual compartments, so it doesn't really matter where they are except for neatness and ease of use.
MysteryInkus: Well, unfortunately it does show that it has its own weight. and some of them are part of quests I've finished ages ago. I've played this game once before, so I know at LEAST some of these items I should have been able to drop by now. Yes I know some of them I still use, but most of it are useless to me. Even if it's not taking up majority of my carry space, it is still unnecessaily taking up space I need for other items. Add up the quests items I can't drop, and the weight starts to build up. I'm trying to find a way to fix it without having to start from scratch and hope the game doesn't have the same problem again.
Well the game doesn't do what you are suggesting it does (clog up the inventory). Attached is my quest inventory at "The Final Trial" stage of the game. As you can see, it only has 14 items in it and every one of them except the Magic Lamp, Ciri's Phylactory and The Eye of Nehaleni weighs only 0.01 units. The others weigh only 0.14, 0.15 and 0.19.
So, two questions: Is your game up to date and are you using mods?