@Outis: And how did she know what blood was in the bags, given that she had just got up.
Also, I'd normally accept magic. But that's like saying someone who'd never heard of the concept of a metre judging a metre by eye. B-negative is an arbitrary name people gave the blood with that cell type. There is no reason for that research to even exist in Grace's universe because they can just heal people with magic.
That's why, when we had to do the surgery on Lambda, I asked if Grace knew what sterilisation and antibiotics and anaesthesia are. Her universe has no need for surgery because of magic.