He was just referencing previous post wishful thinking lol
This. More like mocking the "broken" modifiers. In the case of the primes, they actually made a mistake in the modifiers (not matching the stats on the weapon). Maybe it was copy-pasta, who knows what the problem was. In the case of Blade: Hi, Jishnu's Radiance, and various other WS like the ones I listed above, they intentionally made a WS with different WSC than (most of) the other WS for their weapon type.
This provides at least SOME variety in the gear choices you might make for different WS and is a good thing for a game like this where the fun is in making gearsets. The alternative is to just slap DEX on every dagger WS, STR on every sword WS, MND on every club WS, AGI on every marksmanship/archery WS, etc. As Celebrindal pointed out, this makes for an incredibly boring experience where you have 1 WS set for an entire weapon category.
There are exceptions like fTP replicating WS and whatnot, but my point was the more variety we have in WS, the better. Having an AGI-based katana WS is an interesting oddity that can make gear choices more interesting.