currently iam about to understand how the leveled lists work and how they are connected, one thing i dont know how to accomplish:

how can i decrease the chance of an particular item in a leveled list to show up ingame?

for example:
i made a better version of the "iron_dagger" called "iron_dagger_Q" and added it to all the leveled list in which the normal "iron_dagger" appears and used the same PC Level number.

--> i want the "iron_dagger_Q" to have a 50% lower chance to appear in chests



thanks!

You can't. You have to make a different list then, because only one percentage is set per list, you can't set percentages per item in the list, only level requirement per item. You can, however see the details of the list of the normal dagger, see what all containers use it's reference and add your own list containing your dagger with 50% in each container, but if you use a lot of mods changing leveled lists it might cause severe conflicts.

It might be possible to achieve this via scripting but that is beyond my acquaintence, sorry.