Corrected entry: When they though that Elizabeth was a Turner and they needed her blood, she only got her hand cut. But when Will was about to shed his blood, it was his throat that was going to be cut. What's with the drastic change between the blood getting?
Correction: Barbossa says a bit earlier that they would take no chances and use all of his blood instead of a few drops. Another reason is that Elizabeth's company would have been pleasurable afterward whereas Will would just be a bother.
Grumpy Scot