I get that. It’s somewhat out of character for the show, which really doesn’t utilize that kind of overly-explanatory deus ex machina. That’s part of why it stood out to me; because even divorced from context it is some top tier fighting manga absurdity. But what I do appreciate about it is that it finally something different. Most of the fights are won by the heroes suddenly believing in themselves even harder than before. There isn’t a lot of ingenuity or creativity to the fights in Saint Seiya and I think it really could use a bit more thought into the fight progression. And as ridiculous as the Dohko twist is, it was at least something. It was a lot more interesting of a solution to defeating an enemy than, say, Dragon Shiryu busting out a new dragon punch or the three traitor saints busting out a new laser beam (Athena Exclamation).
My favorite moment is still when Shun was fighting Gemini and used the Andromeda Wave for the first time, making his chain travel through space to attack the pope. It’s another example of the hero suddenly winning because they had finally had enough determination, but it was the first (only outside of Dohko?) time I felt like one of the heroes did something new and unexpected (attacking the true enemy from a long distance) rather than just a stronger attack.
Now that I think about it there are a handful of other moments that aren’t just the hero suddenly believing hard enough (parts of Ikki vs Shaka fight, where Ikki purposely lost his senses) but by and large I just didn’t feel like the fights are solved in as interesting ways as a lot of fighting manga that came afterward.