Thus "historical" suggests pertenance to history, rather than the find, whereas "historic" refers to the age/importance of the find.Exactly. IMHO use of the word "historical" is generally redundant, since the context must be obvious from surrounding text. Whereas "historic" emphasizes the gravity of the occasion.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1