The problem that everyone advocating adding free relics/mythics/empies to the test server are missing, and that a good part of alha's point is based on, is that the test server as SE has implemented it actually works perfectly fine for testing new content prior to it going live, to find bugs/kinks, find out what drops from what, etc. The reason it works is because the people who use it primarily are all individuals who actually know how to test shit and have the patience required to do so.
The test server isn't designed to hold a massive number of people like a regular, full server. If suddenly, everyone and their mother could access free relics/mythics/empies, the limited number of slots on the test server would get hit by a rush of inane BNS melees who want to play with x/y/z relic/mythic/empy for 15 minutes and then never log on the test server again, thus wasting their slot and lowering the number of productive testers on the server, further exacerbating the only real issue the test server has, a lack of people who know what they're doing. Yea sure, adding free toys will increase the number of PEOPLE, but it won't increase the number of testers, because the people who have the patience to test and the competency to understand what they're testing are few and far between in the playerbase.
Basically, the logic here isn't that what you guys want is necessarily a bad idea in and of itself, but rather the repercussions it will bring. Due to the fact that only about 5~10% of the playerbase will ever actually own a finished relic/mythic/empy, they are a desirable item people want to play with. Thus, while you want this:
Add Them: Those who can test but don't have the weapon on live are able to test them for possible new effects in one last update before they launch, after which they won't likely ever receive any more changes
but what you'll get is this:
Add them: number of slots on the test server ~500; ~50 are occupied by individuals who actively test new material in a proper manner, knowing what they're doing and how to do it, ~450 are occupied by Joe-Shmoe-DomaruSam who log in once or twice to play with a relic/mythic/empy and then never log in again but stay on the test server, preventing any new testers who actually know how to test from getting in.
Additionally, THE TEST SERVER DOES NOT EXIST SO THAT YOU CAN FIND OUT IF GETTING X/Y/Z RELIC/MYTHIC/EMPY WEAPON IS WORTH THE EFFORT TO GET/UPGRADE. Any and all arguments attempting to use that as their purpose hold absolutely no water in this discussion, because SE made it pretty clear that the purpose of the test server is to test new content and make sure it all works as intended, and nothing more. The whole reason they made it is their extensive history of breaking all sorts of utterly unrelated crap almost every version update. If you can't find any information about the weapon you want to upgrade, find someone who has it. FFXIAH makes that pretty easy. If you can't find someone who has it, that means no one has bitten the bullet to be the "first" person to get it (I say "first" because while technically, every weapon has now been made, several of them have no information due to the one~two people who made them not being the "test shit and give people answers" type of individual). If you want to know about claustrum (first example that popped into my head after reading the thread), but can't find anyone who has one, then you're left with the option to either stop caring (which would be wise, because lolclaustrum), or to suck it up and upgrade the damn thing yourself.
If SE were to simply say: "Yes, we're adding new/changing/increasing the hidden effects of relic/mythic/empy weapons from level 95 to level 99" or "No, we are not adding new/changing/increasing the hidden effects of relic/mythic/empy weapons from level 95 to level 99" then this entire discussion would become moot. If they say they are, then they're shit they want us to test. If they say they aren't, then there's nothing to test.