That would be a perfect fix. And it would free the rare binary artifact removal that can be completely useless.
Actually leave the 'detroy artifacts' to those cards but give them another row dependent alternative.
Combination of dual-purpose card with artifact removal property, and armor on artifacts (which makes sense since they're objects) so you can spend damage value to remove them, instead of swinging points, would make really good artifacts (like old sihil or tainted ale, more healthy for the game).
With the increase in power for low value cards, put the witcher trio back to 3. 9 power and 2 thin is not worse than portal for more provisions.
Coral and Birna are fine, they need more synergy but that's an archetype issue. The cards themselves are good.
Savage bear is more than fine. 4 power and 2 damage with zeal is already better than NR equivalent (mauler, that is row locked, no zeal) and can go up to 4 damage, or more if you copy it.
Nivellen's ability is fine, but he could use a power or provision buff, yes.