This medal is part of a series of gold and silver bullion pseudo-coins issued as part of a hypothetical global currency system by Werner Graul, a private individual in Germany. "IIS DUC" is the denomination in Latin, 2 and a half ducats. It is indeed struck from .980 fine gold. The weight should be 8.625 grams (.2718 ounces).
You can find many different types of these "coins" listed in the Krause "Unusual World Coins" catalogue, or find it on Krause's website, Numismaster. However, this particular piece isn't listed; perhaps because his standard obverse has been replaced with a city-view of Nuremberg, and it's not entirely obvious at first glance that this is indeed part of that series, but it is; the denomination mark and six-armed cross are the same.
This AllExperts page is one of the few neutral references I could find about any of these items. According to the catalogue (which the Expert in the above link quotes) these "coins" were struck at both the Hamburg (Germany) and Vienna (Austria) mints, presumably whichever was cheaper at the time.
Werner Graul went by the pseudonym Aureus Magnus, and
www.aureus-magnus.com is the website run by the family, where you can still buy these medals. The website is in German but this link takes you to their issues from 1968 to 1981, whch includes a pic of the 5 ducat version of your piece (catalogue number 70). A translation of the "about us" page reveals the "coins" were indeed briefly sold through banks.
It's my understanding that quoting a mintage figure would be meaningless, because Werner had, and his son Jurgen still has, an "open mintage" policy and will strike any piece to order; as far as I know they're still being minted. So they're not going to have much of a premium over bullion value.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis