Equipment items in the game all have a "base", and that base has fixed stats on it that apply to all items which use it. Take the Soul Seeker, for example. It's base is the Radiant Scimitar. The reason the Soul Seeker has a "weapon damage" rating of 12-14 is because the Radiant Scimitar does.
If the damage rating of the base item was changed, all items - either pre-patch or otherwise - would see the same change.
However, there're obvious differences between the Seeker and the plain Scimitar - The Seeker has a special colour/title, a swing speed increase, and so on and so forth. You can't change these things by messing with a base item, they're applied specifically to each artifact on a case by case basis. And users can customise these items further with stuff like Tokuno dyes and so forth. Imbuing will let us take that further still. But one thing we won't ever be able to change is the base stats on an item, such as swing speed (we can add the SSI property, but we can't change the base swing speed listed on the item).
So, given this, you should be able to see the difference between the Talon Bite patch and the Quiver of Rage patch.
With the
Talon Bite, they just tweaked the stats on the base item (
Ornate Axe). Boom, hey presto, suddenly every single item based on the Ornate had it's stats changed.
With the
Quiver, they needed to change stats that didn't apply to the base item at all (the custom damage type properties) - they actually had to change all the QoR's out there individually.
If any QoR's still exist with the old mods on them, then that means they somehow missed some of them. No idea how. Step one towards getting it fixed is providing proof to the devs that some of the items missed the change sweep.