Specifically, buff Silence vs Sanctuary!
I think Silence is niche enough without Sanctuary protecting against it. Anyway Sanctuary says "your hand cannot be altered during your opponent's turn" - but Silence doesn't alter your hand, and it's impact certainly isn't felt until it's the Sanctuary-player's turn.
In terms of how much play each card sees, Sanctuary gets a lot of play, while Silence gets pretty little. This trade-off just gives players more reason to run Sanctuary and less reasons to run Silence