Expose her buttocks

You decide to take your time with her. You move all around her in a blur, stopping at regular speed just long enough for her to notice you appearing and reappearing at various places around her. She tries turning around awkwardly to face your position each time, her legs having been essentially hobbled by the pants pooled at her ankles. Having the girl shuffling in circles while down to her underpants adds to the humiliation.

Then you decide to strike, appearing behind her, pulling her panties all the way down across the curve of her ass, and finishing it off with a smack of your hand against both cheecks, sending them wobbling like jelly.

The knight jumps up in surprise, squeeling in embarrassment, but unwilling to relinquish her grasp from her breasts long enough to pull her panties back up.