It's natural to be nervous, if you've never had certain medical procedures before.

[then nehan takes venti's arm in hand and traces a path with his other hand, starting from the man's wrist.]

The wrist is a common place to cut because of all the prominent veins... but I don't want to kill you. The elbow has very obvious veins as well, but you'd want full functionality of your arm afterwards. [then the erune pokes at a spot just below the elbow.]

Right here, this should be fine. Veins can easily be encouraged to come up, and it's easy to heal from a wound here.