Buckingham reaches for the mask, listening. He deems her explanation worth a loud laugh and a rather cheerful expression.

"Then this shan't even sting!"

And this? This is Buckingham grabbing not George's mask, but her wrist instead. This is the duke freeing a knife from his sleeve all too swiftly as he pulls her closer. This is a paranoid man thinking he has to be faster, because it will be her life or his.

This is him aiming right for her heart.