Don't forget - there is a reason diabetic blood testing has used finger pricks for decades. Reliable, easily managed, easily cleaned, and while a bit of an annoyance, not debilitating.

For arcane rituals and such, maybe the palm gives more control...or it is simply supposed to suck more to power the magic (makes it more of a sacrifice than using a few vacutainers to draw from the antecubital with no muss, fuss and just a cottonball and a bit of coban).

- M