Can anyone tell what mint it is? It may be HAT in the exergue? But that doesn't seem to work with the II in the field.
I general you need to treat coin attribution as a "multiple choice" test (matching to known varieties) rather than assuming that the legend/mintmark/etc could potentially be anything ...
Of course, this means that you need to be aware of the "multiple choice" selections available, and for late roman bronze one of the best resources, which is also free, is Helvetic'a RIC spreadsheets which you can download here:
http://www.catbikes.ch/coinstuff/coins-ric.htme.g. in this case, you'd look at the FEL TEMP "soldier spearing horseman" spreadsheet, and if you filter by the "II" in left field, than you'd see it has to be one Siscia, Thessalonica or Aquileia, and you can see what the alternative mintmarks are and which one this most looks like. Since none of these start with "H", then you'd realize it has to be a sloppy (but typical) "A", and arrive at Aquilea as Victor has indicated.
What's useful about these spreadsheets rather than other reference sources (e.g. books, or some web sites) is that you can use pull down menus to filter by whatever you can recognize on the coin, to narrow down the choices which you can then match to the coin.
