I've always been bothered by writing "as" which in English can be very confusing. I like your convention (if it is) of capitalizing... will do so from now on!
I've been capitalizing As for decades, so already in my first article on the new Nilus As of Septimius Severus in Num. Chron. 1970; don't remember for sure whether copying the convention from somebody else (likely) or introducing it on my own. One could also italicize as and the other denominations (denarius, sestertius, etc.) to indicate that they are foreign words, so also distinguishing the denomination as from the ordinary English adverb and conjunction 'as'. But I think most of us now consider these denominations to be ordinary English words, so not in need of italicizing.
Going back through the mists of time, the first ancient that I acquired, but no longer own, was an Alexander III tetradrachm, of Salamis. However the interest that I have in ancient and world history (and herstory) goes back even further, to the 5th grade in Detroit, where I learned of the great Athenian victory at Marathon in 490 BC. That clinched it for me. That planted the seed of interest in me of all things Athenian. Over the years I have acquired quite a number of coins, both ancient and world, but the coinage of Athens has always had a special place in my heart. Here's the mass production Athenian tetradrachm that I acquired in the early 1980's from Harlan Berk, and it is the most senior member of the ancients collection.