I don't think you can question Weight's mental focus. DW's a professional and a class guy. Any veteran would give their left nut to win a Cup and Weight has that chance with one of the best teams in the league. Plus, I'm pretty sure he knew he was going to be traded at some point before the deadline. I'd be willing to say that having that element hanging over his head would affect his mental focus more than the event of being traded itself.
He's a UFA at season's end and he can go wherever he pleases. It would be foolish to not consider all the options, but if he has a home and family established in St. Loo, I'd expect him to go back there, play a few more years and retire a member of the Blues.