Actually, empirical tests only apply to physical reality that is mechanistic or predictable by nature. Can you show that all reality is predictable by nature? To presume physical reality is “all reality” is an assumption that predetermines the manner by which truth is determined.
At the first instant of the Big Bang, could you have predicted the outcome?
Can you show an empirical test that demonstrates conclusively that all reality is subject to empirical testing without simply presuming that it does?
What constitutes moral agency depends upon a definition of what is moral. That is not an empirically bound question. To insist upon an empirical answer is simply to be confused about the nature of what the word moral means.
The nature of morality depends entirely upon the nature of the “good” or “end” towards which moral beings are ordered. That is a teleological question, if it is to mean anything. Empirical tests rely on the presumption that the way things are is the way things will always be, that you can predict the future by an understanding of past events.
The problem with that presumption is that good, better, best are completely outside the scope of empirical analysis. It cannot say one outcome is better than another, simply that one outcome is more likely given the causal conditions.
How do you measure courage empirically? It wouldn’t make sense to exhibit courage unless the odds were very much in your favour. In which case you are not exhibiting courage at all, but rather taking the most favorable course. Courage would simply be empirically untenable. As would all other moral virtues under a restrictive empiricism.