I dunno, as I explained before I think it's a bit of a blind alley.
If they make them too weak/useless, then what's the point? Nobody (almost) would care, and it would feel like a waste honestly.
If they make them too strong it might make some relics/mythics/empys feel like a waste, we would be back to the old level 75 situation of many of those weapons, where wielders were using WS to pop aftermath, and then spamming another "normal" WS.
They need to make these WS strong but not too much. That's that they need to do, probably, but it won't be an easy task, and it will make the gap between "
relic/mythic/empy" and "
normal weapons" more narrow than it is now. This will make some of us happy... and then some other unhappy.
They are called "final WS" in the jp text, and they were called this way even when presented long time ago.
Of course, the fact that they are making them with "final" in mind now, doesn't mean they'll change their thoughts in, say, 5 months. Nobody can tell of course

But as of now, as far as we know, they are planning those with the concept "final" in mind. D: