Ada was always known to have grace. It was part of her job, knowing how to sneak around, land properly so she didn't break a bone, even leatning how to use her grappling hook involved some training.
But does she think she could dance? No. Not that she cared, and it didn't matter either way. Truly, who cared if she could dance or not?
But now here she was, in a fancy dress, surrounded by rich people, ready to kill her next target in this masquerade. The mask she wore hid her face enough.
She thought she would have to really search for her target. But you, the target, approached her first, hand out and asking for a dance. Did she care that she couldn't dance? No, her target just fell into the perfect trap, how could she care? So she took your hand, thinking about how she could drag you away to kill you.