As much as I like Toronto, I can say this: we spent two weeks in Nova Scotia in 2011 and it was barely enough. We certainly didn't see everything.
You got good suggestions for day trips out of Halifax. I can recommend them equally. Lunenburg / Mahone Bay are gorgeous communities well worth your time. Peggy's Cove is a giant cliche and yet ... irresistible. Make sure you go - early in the day when it's quieter. A bad weather day might even be better.
Cape Breton is fabulous. Stay a few days in Baddeck and you can do a day trip to the Cabot Trail and Cape Breton National Park, and a separate day trip to Sydney where you can go to the fabulous Louisbourg historical reconstruction. (Arrive at the gates at opening ,and plan to spend the day; it's that good.)
The Bay of Fundy coast is equally beautiful and worth a visit as well.
Do Toronto and Nova Scotia as separate trips, unless you can afford three weeks or more.