No Number Scaling
Brings the scaling of vitality, damage, and armor to virtually 0. This means that characters and items at level 1 will be about the same number wise as those at level 20. Numbers will increase slightly from more constitution and item stats, but this should be relatively minor. All the numbers should remain their relative balance, so balance should be relatively unchanged, other than the fact that level difference will have a much smaller effect. Using a weapon above your level now only gives a 1% hit chance penalty per level it is above you.
It’s safe to apply it on an existing playthrough, but if you decide you want to remove it, unfortunately enemies actual health won’t scale up (their maximum health will, but not their current health, so they might end up with with 30 of 300 health, for example). However I have a "vitality fix" for this, which heals enemies on starting combat, if you decide you want to revert to vanilla.