Brandon kind of wrote himself into a corner with Gawyn. He spent two books emphasizing his skill. And we know from Galad that Gawyn knew how to use the Flame and the Void too. So I would have expected a better presentation of that end, where Gawyn, in typical fashion, ignores advice about the rings, and uses three at once. I'd have expected the use of the three rings to make it impossible to focus, to find the void. And that would be his downfall. As such, these holes and inconsistencies spoiled what would have been a very good end to a very irritating character. At least he served the only useful purpose he could have: energizing Egwene enough for her to go all out.