Aqua fortis, literally strong water, is nitric acid.
Iron dissolves in nitric acid and forms iron nitrate or as it is also called, ferric nitrate. We call these ferric nitrate solutions aqua fortis, but that name is in fact a misnomer.
Apparently this misnaming may date back at least to the late 1700’s, at least judging by TOF’s post. But if they said aqua fortis, I think is most likely that they were referring to a nitric acid iron solution, and not an aqua regia iron solution. These acids have both been known since the 1300’s, and their reactions with metal and wood were understood long before the 1700’s.
If Wahkon Bay’s aqua fortis is really aqua regia, then it is misnamed.