I don't think Witcher is that bad. It's just very situational. I think maybe no-keyword decks need to be made a bit more appealing (perhaps by adding some commons or uncommons with low-keyword synergies), but I don't like the idea of changing Witcher's mechanism, because I think it's cool as it is.
Here "very situational" *is* bad because "very situational" also means "useless most of the time." And yes, reworking can be done through adding a lot of good "no keyword" cards but obviously it's a harder and slower way.
If a card is only useful in 1 out of 100 decks, but in that 1 deck it's really useful, then I think it can still have merit. Witcher is a card that I have taken in a few decks before, and which can be incredibly useful in certain deck types. That's more than I can say for quite a few other rares.
If we are going to buff Witcher, I would do so either by:
- Increasing the damage he does per card
- Making more cards that support few-keyword decks.
I would not do it by changing the card's mechanism though.