As per the title, I'm not sure why shadow needed an outright damage nerf. And putting it on Grim Focus just makes Assasination synergize BETTER with Herald of the Tome, which I'm pretty sure is the exact opposite of what goal is. I've argued that Grim Focus should have Brutality and Sorcery to better fit it's original function, and I still think that would be reasonable. However, the more I think about it, the more I think that it doesn't need ANY passive buff. It's already an extraordinarily powerful damage skill on an extremely powerful damage line. People would still be using Assassination and Grim Focus if it just had the active effect, and for good reason. Taking damage out of Shadow just hurts pureclassed Nightblade dps more than they're already hurting.