If there is a western equivalent to the item then the english name will do fine. I doubt many of us speak japanese. It's why I wouldn't like this item have an arabian name.
On that note, they could at least give the Japanese armor a proper name. Doesn't have to be in Japanese, but something of an english translation of the Japanese name, or just something appropriate, like "Japanese Lamellar armor" for the Heavy and Medium armor, and "Japanese Leather Lamellar armor" for the light. Would be better than "Heavy Strange armor" etc.
Caltrops were already used in Roman times.
Yeah, but the item being suggested is Japanese.