While Colleen Wing was fighting Bakuto (Colleen's former trainer and member of The Hand), Misty jumped in the way and stopped him from cutting Colleen's head off. In the process, Misty had her arm chopped off at the elbow. After the big fight was over, Colleen visited Misty in the hospital.

How did Misty lose her arm?

In the comics, Misty Knight received a bionic steel arm from Tony Stark after she lost her right arm in an explosion. The prosthesis was later replaced with a new upgraded version made of a vibranium and diamond alloy. Following its destruction, Knight proposed the idea of a more "blinged out" prosthetic.

When did misty lose her arm on Luke Cage?

Netflix's Marvel superhero series is returning June 22. Right. It's an iconic aspect of the character from the comics. Misty's arm is severed in The Defenders, so it felt like a given that she would gain her mechanical arm in season two of Luke Cage.