Not to pile on (it honestly feels a little mean at this point) but you seem to be picking on some of the already weak classes. Bards and Warlocks are not really at the top of anyone's list in their respective roles. Warlocks do the least damage of any striker. . .about all they have going for them is their versatility and control. Taking that away is kind of mean.
If you want nerfs, focus on Rangers, Fighters, and Clerics. They are at the top of their roles, and there are clear outliers for each class as far as power goes.
Also, singling out the wintertouched/lasting frost combo without addressing the radiant weapon or daggermaster or any other kind of cheese is odd. If you are going after that one thing for a reason, then it is probably best to go to that one player than to eliminate it entirely from your campaign. That feat is not worth it, I can't imagine anyone taking it, ever in that form.
Jay