Err... is this not a bug nevertheless? If the Gladius is supposed to be flux starved, the Gladius' flux stats are the correct place to facilitate this.
Making one third of its weapons more expensive, when this weapon is also the sole weapon of another fighter (the Lux'), obviously harms the Lux more than the Gladius.
(So we can "intentionally" make the Lux' flux stats higher than they need to be, but... why so convoluted? Who is supposed to keep track of that and why do they not have anything better to do with their limited time and attention span?)
I'd... yes, assert... that this cannot - must not - be the proper way to do it. If nothing else, this makes it extremely hard to spot a real mistake. Any typo, any skipped line, any accidentally saved tab turns into "meh, probably intentional, could bother the developer to find out, but that detracts time from the regular development cycle, better keep it quiet" that way.
(And of course, after some time, it's harder for everyone to tell, no matter whether player, developer, tester, designer, whatever. It's a lose-lose situation.)