Does it fit? No.
In the Warhammer 40K universe? With thousand of world and culture, where a lot of then fall back to middle age (and beyond) technologies? And where this elfe mage is not far away from an archonte eldar with a runic blade?
Let's say yes.
And in fact, since the imperium kill most of the time all non human sentient race on the planet their going to colonize, quite usual, (just too boring to be played).
Back to the point, CRPG got no background, no story, no timeline, not even sure we could say it's take place on calradia since the map maker make the map like they want.
Only thing we can use to justify something is the stuff, and weeaboos stuff is here since the beginning.
And when a lot of player got their equipment as credible than a WW2 GI with a rapier and a viking shield fighting a caveman with a two handed sword (Maybe a little harsh here ^^). I will say Weeabos are just as credible as the rest.
By the way, western armours somehow kept in Asian style? Mongol Empire, China to Poland, year 1274
