"I am not a physician." She rose to her feet and extended her hand towards him. "The hand you pulled these from, if you would."

She wanted to see the state of his hand up close. To see if the nails had truly been replaced or if perhaps they were still regrowing. Not to mention the fact that these blades were somehow too long to have been inside his hand which meant some other process was taking place inside the body.

Now if she could figure out a way to get him to use this ability consistently...

Clearly she wasn't bothering to decide if this would kill him or not. She was far more interested in how it worked and how to make it work better.