A few points to add to this thread.
Another clear theme in the books is that reality fades to myth and myths into legends... Almost all of these examples of old school False Dragons can be chalked up to poor information being passed down over a thousand years.
Aviendah's assessment of Egwene's strength isn't that far off ... Amy's and Melaine are both on the string side of any AS scale. Merise is likely close to Melaine and Elza somewhat weaker ... This jives with Cadsuane being somewhat weaker than Egwene yet still not more powerful as Merise and Elza combined.
We've seen in multiple occasions that channelers do not have to actually link in order to build strong shields. Rand was held by several independent shield weaves that still allowed each sister to remove herself from the shielding ultimately leaving him down to 3 shields he could crush. IMO these women were not actually linked because we saw each point of the overall shield and that parts of that shield could be converted to knotted points while the rest was maintained. Compare this to the shielding of Nynaeve by Ispan and Falion they were clearly in a link as were Corele, Daigian and Coiren(?) who held Semirhage. Linking forces the ability to be directed by a single person and the benefits are increased power and dexterity.