The drawback to the Chameleon Arch was that the Doctor remembered everything she'd done as a human.
"Oh no! No! Don't you dare, Steve Rogers. Don't you think about it. I am going to hate myself for long enough as it is. You are bloody well going to live through this!"
The advantage to being a trained soldier in tactical gear was that she had equipped with some first aid supplies. She started to pull them out immediately, not daring to move the knife from it's position. The fact that it remained in might have been the only thing keeping Steve from bleeding out right then and there.
The Doctor was panicking. He looked terrible.
She barely noticed the way Thor's large body cast a large shadow over her. It wasn't until the prince carefully took Steve and scooped him up into his arms that she registered what was happening. Thor flew off quickly with Rogers. Thankfully the healers on Asgard would be able to stabilize his fragile body quickly.
The Doctor met Bucky's eyes, her own sparkled with tears not yet shed. "I didn't know... I'm so sorry. I'm so, so sorry..." she begged.