First off, Sansa has turned into an absolute badass. The long suffering boredom of her plight has certainly made this pay off more than worth it. This is so much better than her last "I'm a strong person" event when she left the Vale and did the emo-makeover. That was groan-worthy, whereas her interaction with Baelish last night put her up there with the greats who can command armies with their voice alone.
That was, best I can tell, the very first time you ever see Baelish actually scared. There's been plenty of times he's faced the barrel in the past and did it with his sneering confidence but last night he looked genuinely terrified that he wasn't walking out of that barn alive. He's faced down the council of the vale, Joffrey, Ned Stark, the Lannisters, and screwed them all with an unmatched confidence and bravado. It was Sansa
ing Stark that finally rattled him. And yes there was the backup from Brienne of Tarth that gave Sansa some confidence and backup muscle but Sansa is finally the first person to figure out his bullshit and recognize him for the sniveling weasel he is. Just an amazing interaction.