Some great payoff to Arya reusing the a similar switch move she pulled on Brienne, and obviously with the dagger that started the whole show's conflict.
The dagger's timeline from what I can recall:
- Dagger used by the assassin to try and kill Bran,
- Catelyn Stark brings the dagger to King's Landing to find out who sent the assassin,
- Littlefinger claims that the dagger was stolen from him by Tyrion,
- Catelyn gives the dagger to Ned and leaves to capture Tyrion which starts the whole conflict between the Starks and Lanisters.
- 6 seasons later Littlefinger brings the dagger back to Bran,
- Bran then gives it to Arya.