Vaivora has become the staple for weapon ichors, but increasing the vaivora stages does not feel rewarding.
How about giving the users additional customization options by adding skill gems to the vaivora ichor to unlock additional effects at Vaivora lv 2,3 and 4?
lv 2 -> +2 skill levels
lv 3 -> -30% Cool down time
lv 4 -> +20% final skill damage
Every skill can only be strengthened once, so the lv1 skill (to put in an example, Pandemic on Necrosis Vaivora) cannot be selected for the lv 2,3 or 4 slots
you put in the skill gem/monster gem you drop in the fields/from gem boxes that match the class of the vaivora to receive the effects for the specific skill
to give an example, lv 4 Vaivora Bow - Reinforced Bowstring
in the first socket(lv 2 Vaivora), you can put every Fletcher skill gem except Barbed Arrow to have its skill level increased by +2
in the second socket(lv 3 Vaivora), you can put every Fletcher skill gem except Barbed Arrow and the one you put into the first socket to have its cool down time reduced by 30%
in the 3rd socket(lv 4 Vaivora), you can put every Fletcher skill gem except Barbed Arrow and the ones you put into the first and second socket to have its final damage increased by 20%
Edit: This suggestion can also be taken as a blueprint for alternative vaivoras that have no skill effect and instead allow the user to decide its skill effects by utilizing monster/skill gems.
Alternative vaivoras (mk II because why not) could be crafted from a vaivora existing for the same base class at Teliavelis in Fedimian, allowing you to choose from all classes in the same class tree of the base class which the vaivora weapon used as crafting material belongs to.