Yes, I was about to say something like this myself, that is, that "a final arrow" implies the shooter still has some more in the quiver, whereas "the final arrow" implies the quiver is now empty. BUT...that ceases to be the case if we add a phrase: "He shot the final arrow of the day." Which leads to another question: Could we substitute "a" for "the" in that sentence and have a "grammatically correct" sentence? My own feeling is that I would consider "He shot a final arrow of the day." as being "uncolloquial"--really meaninging that it is "ungrammatical." Norm Carlson