Lloyd Alexander's The High King: The Return of the Magical?

A thought, and a challenge to 'The Doom that Came,' the avuncular and popular blog that focuses on speculative fiction literature:

In a recent (cough: October 2011) entry, Doom extolled the virtues of Lloyd Alexander's beloved fantasy quintology (if that is the word, or at least a word) for children 'The Chronicles of Prydain,' a fantasy series second only to 'The Chronicles of Narnia' in prestige among the genre, and probably first in quality (much love to CS Lewis for being a pathbreaker in children's fantasy, but he had some substantial limitations as a writer which Alexander did not share), in particular its first volume: The Book of Three. Among other things, Doom noted the exceptional magical content of this first volume was not shared by its successors:

"One major reason that my opinion of The Book of Three varies so much, from one reading to the next, is that the book is quite different from the others.  There’s much more magic about, and this makes the whole atmosphere of Prydain feel different.  Both Gwydion and Eilonwy cast magical spells in the first book, something the prince of Don never does again and the princess of Llyr never again of her own volition.  When Gwydion later resists the tortures of an evil enchantress, he gains the power to smash aside the walls of his prison and then to speak with animals.  Another mighty castle, once the seat of Prydain’s kings, is thrown down into flinders by a massive explosion when the holy sword that lay immured beneath it is stolen.  In fact, much of the book reads like a (rather action-packed) travelogue, as the main characters visit the evil queen’s doomed castle, the valley where Medwyn lives and which only animals may ordinarily enter, the underground realm of the Fair Folk, and finally the golden castle of the Sons of Don.  In a way, the reader is introduced to all the wonders of the land, side by side with the protagonists.  But when they revisit that same land in their later adventures, it often seems much less magical, and the magic they do encounter is less awesome, sometimes even tawdry."

The whole thing can be read here:
http://doomthatcame.wordpress.com/2011/10/19/the-book-of-three/

My question is simple (HUGE SPOILER ALERT). I haven't read one of these books in at least fifteen years, though often enough before that. But doesn't 'The High King,' the pentology's (maybe that's the word) last volume mark a partial return to the more overtly magical nature of the first volume? Partly this is to be expected: four books of development pay dividends in the final volume, and these returns are in part magical and metaphysical. Nevertheless, don't we see Dyrnwyn, perhaps modern fantasy's prototypical flaming magic sword, do wonders once again? Don't the animals who led our protagonists to Medwyn's hidden valley in the first book return to 'take vengeance' against the evil Huntsmen of Annwvin' (spelling) when the latter are pushed into a tough spot? Doesn't dark turn to day (through magic means), and the iron crown of Annwvin burn through the skull of a pretender king? Don't the immortal fates show their true form, doesn't a book strike down a man with fire, and a deathless race meet their match?

All this must be measured against the nature of the book's conclusion (side-note, Alexander writes better endings than anyone), which cuts against magic continuing, and involves the Fair(y) Folk closing their doors forever. But I'd be interested to see any response Doom That Came has on these or other scores.