yeah i was unable to find an official reading of his sword name, so i just used standard on'yomi since it's a 2-kanji word. But now that I looked again, I found the article for Hakumen on a Japanese fighting game wiki, and it agrees with your reading of "ookami", so i'll edit that in my above post.
and you're right, this usage of Japanese is a kind of "warrior poetry", almost.
陣 (jin) isn't "field" like what you're thinking; in Japanese, that kind of geometric or physical field is 場 (ba). 陣, itself, means "battle formation; camp, encampment", and when it's combined with other words, it's always used to refer to members of a group or squad in a kind of (battle) formation, if i understand correctly (although there are figurative uses of this word that don't strictly adhere to that image, i think).
for example, if you say 円陣, it means "(a) circle, ring", with the nuance that it has been formed by a group for the purpose of offense/defense.
but it's not *only* used for battle purposes: 教授陣 (kyouju-jin) means "faculty" (of professors, like at a university). but it differs from just 教授 because it has the idea of a kind of "line-up".
then again, maybe it's a reference to a kind of "base"/headquarters? not that i can think of *why*, but i guess if you have the right story-mode info, it could work...
also, just to make it a bit more complicated, the word 魔法陣 (mahoujin), in Japanese fantasy fiction, means "magic grid/matrix/circle", like what we would think of in Western fantasy fiction as a protection/warding/summoning circle that a magic-user could create and use. So here, 陣 is being used to sort of instantiate the idea of "a (geometric) formation of magic" -- so in that sense, 虚空陣 could be like "The Void Circle", or "The Void Grid" or "The Void Matrix" lol. Well, idk, I think void matrix sounds funny, as a math student, but I guess it could work in fantasy fiction.