I’ve come across people who distinguish vital energy from “power” as they described it.
Really?Usually when I see people talking of vital energy they also speak of it as an energy source for power(as action is dependent on power, we move because we have the power to do so due to the energy flowing through our bodies, so it makes sense that said vital energy also powers up whatever it is they're doing).
A good example of that is Qi or Prana.The energy that powers up your body and helps you be healthier and stronger in body.
Then you have the concept of Mana(and here I speak of the "spiritual energy used in magic", not the mana of Hawaiians which is less about magic and more about personal charisma and ancestral power/status), which is not an energy one couldn't live without(so it isn't "vital energy") but a reservoir of a substance that powers up spells in fictional works.
Is this a form of vampirism or the manipulation of natural energies in all things?
I don't see how this would be linked to vampirism, but then again I'm no expert in vampirism.But yes, it does seem tom imply the unseen and barely felt energy that links everything in nature, though if that can be said to be a proper energy, a spiritual link, a "being" or even a big unknown that we may never understand, that's a question hard to answer.
After all, personal bias can also colour a person's perception of any subject.To some this will be god givingthem blessing, to others it will be not unlike a kind of entropy.