That's a good point. I'm probably overestimating the usefulness of aluminum in this context.
I think it would basically fill the role of mithril. Neat very very expensive weapons/armour held as a royal treasure. A status symbol far too valuable to actually be used. With the occasional exception (radioactive hobbit stumbling into some in the swamps of N'ork).
A reminder for everyone: on this day in 1983, Stanislav Petrov saved the world.
It occurs to me this time around that there's an interesting relationship here - 9/26 is forgotten, while 9/11 is remembered. Do something charitable, and not patriotic, sometime today.