Earlier quoted context omitted.
There’s the rub though: what you’re proposing isn’t measuring “subtle energy” at all. It’s measuring whether or not there’s some phenomenon (possibly psychological) that brings pain relief. Your proposed test is only measuring the effect (which is a valuable test!), but not providing any insight into the mechanism of action.
Technically, that is also true when studying energy in physics. You can't ever measure it directly. Only indirect effects. From that we build models. And one of those models contains a quantity called "energy [physics/chemistry/etc]" which is in fact a highly abstract concept that doesn't correspond to any actual object in the world. Technically it doesn't even have a definite value in any real system. But we take it…
I'm also a reiki master.... And the CTO of a 2 person Signals Intelligence startup. I'd like to think I'm not conflating EM with "energy"(occult). Btw I hate that word - there's a definite meaning and the occult way it's used doesn't replicate known science. Maybe we should use Mana until we can define what it is.