Sabotage her entire outfit

Time slows down at your discretion. The knight has slowed down to nearly imperceptible movement. You approach her, getting a good look at the way her outfit is structured; plates buckled on top, pants and gambeson shirt underneath.

You get to work. First you unbuckle the straps of all the plate armor, them you reach underneath. You undo her belt, reach into her pants to get a good feel, exploring hands sliding up to her crotch and feeling through her underwear. She's wearing a garter and stockings, how naughty. You unclasp the suspenders and undo the garter at the back. Then you reach up her back and undo her bra.

Some items of clothing aren't going to come off by themselves however. You zip around the local stores and find the local tailor's sharpest scissors. First you simply snip the sides of her panties, and put a few cuts in the waistband of her pants to prevent it from staying up. Next you set to work on the gambeson, cutting the shoulder sections, and cutting the sleeves loose from the torso. That ought to do it.

You return to your original position to watch the show unfold.

Time resumes, and you watch intently. At her first step, you can see the plate armor shake. At the second, gravity can no longer hold them in place and they begin to fall off, clattering to the ground. By the third step, her shirt starts falling into the pieces you turned it into, the torso sections falling away and the heavy sleeves sliding down her arms, her belt and loincloth give way, and her pants slide down to pool above her ankles.

Underneath, her unclasped bra just falls away, as does the garterbelt. The suspenders flop uselessly from her legs, and even her stockings don't stay up entirely. With the waisbands cut, her underwear simply falls off.

All of this happens in the space of seconds. To an outside viewer her outfit simply collapses into pieces, metal clattering over the floor and fabric pooling around her legs. The knight feels all her clothes falling away, stumbles and screams, clasping an arm around her unleashed, bouncing breasts, and sinking down into the pile of clothing, while trying to hold on to any remnant she's still wearing.