We have discussed from time-to-time whether certain weapons qualify as "ethnographic" for the purposes of this forum (by the way, the name has changed to "Arms & Armour," so we are allowed to discuss non-edged weapons as well
).
What is ethnic to one person is cultural to another. From our Western point of view weapons such as tulwars and keris are "ethnic" because they come from other cultures. On the other hand, our Indian, Malay and Indonesian colleagues would rightly view a US Civil War sabre, a rapier, or a Viking sword as "ethnic."
My view is that any weapon that is specific to a culture meets the definition of "ethnographic." This basically excludes fantasy weapons, or weapons so generic that they are not identifiable as belonging to any particular culture. A switchblade, or a modern machete or handgun could fall into the latter category, for example.
As a practical matter, we don't see much discussion here of Western military weapons, medieval and earlier European weapons, or nihon-to, because collectors of these weapons tend to form a distinct group apart from the collectors of other weapons.