TLDR: Halt skill progression instead of regressing, mainly farming skills atleast.
So i think the skill system is subpar and with the mistlands update it got worse, since even more skills got added to regress. The problem is its WAY to grindy since you do lose skill levels. So either this should be way faster to level, so that changing weapon types and back doesnt reset you as much if you die a few times.
The better thing in my opinion is to incur negative exp to your skills that are capped. This results in skills that CANT stagnate, but WONT level if you dont use that skill actively. While this means chopping a tree here and there will probably not get you any exp, atleast you dont get punished by dieing in combat, when you just want to build occasionally and have to find out your farming skills regressed 10 levels+. Someone who is mainly building and farming materials wont suddenly lose hours of skill progress, but keeps his efficiency, leveling once again later on.
It basically just caps the amount of punishment and could even replace the "no skill drain" buff.
Source: https://www.reddit.com/r/valheim/comments/11i0552/skill_system_change/