Why is it none of the silver saints recognize that Aria isn't Athena? Because all of the old silver saints were killed before the Hades Arc, and Athena has been in hiding on her island due to her arm infection by Mars. Mars is taking advantage of her being a recluse to use an impostor who (Anime Hair aside) doesn't even look remotely like Athena.
Remember how Mars seemed very interested when it was revealed that Kouga had a powerful light element? Now we know that Kouga was actually a darkness user, and that this was apparently a major factor in Mars's plans, justifying his interest. He legitimately wasn't expecting Kouga's element to be light. This might also be the reason for his sudden intervention when Kouga's light element flared up.
A meta example. Remember how the eye catch showed the pegasus cloth crystal and then a faint black one briefly beside it. Kouga's true element is darkness, the eye catch was showing the hidden truth.
Another meta one in the choice of choosing the Roman god of war, Mars, rather than the Greek one, Ares. When it comes to the Japanese pronunciations, there may have been some confusion with the already-existing Gold Saint of Aries.
Putting it back in-universe: he wasn't born a god incarnation, but became one after losing his first wife drove him insane. Furthermore the idea wasn't to be another god fighting Athena for control of Earth, but to establish a new society on another planet—Mars. Him not sharing the Olympian naming theme suddenly makes total sense.
Also in Mythology Ares usually lost and had his rear handed to him on a silver platter, which is to say embarrassingly. But Mars was treated with more respect by the Romans compared to the treatment of Ares by the Greeks, to the point of being THE War God, Athena was demoted as Minerva. So the idea could also have been to establish that Mars was a big threat.
Fridge Brilliance meets Parental Bonus: Shiryu seems to be a happier man after the Mars chapter. While it can be said that he's just happy that his son is safe and the Dark Cosmo infecting him is gone, one can also suspect that he's happy because there's now a chance of him and Shunrei giving Ryuhou a younger sibling.
Palaestra was originally built to get saints prepared for Mars' return. Now it's revealed to us that the TRUE purpose of the academy was to absorb the saints cosmo and the killed them.
How many people died of the curse of darkness before it was finally eradicated from the face of the earth in episode 51.
Kouga himself saw Athena taken away by Mars. Yet he's still convinced that going to the Palaestra and winning Saint Fight, conventional means of meeting Athena when she's not in the middle of a Holy War, means finding her.
Now that we know the other Athena is a fake one this one is probably justified.
But that doesn't change the fact that Kouga himself leaned that Saori was Athena and saw her taken!' Yet we don't get a single "You guys are Saints. How come you're not freaking out? I thought she was kidnapped!"
Kouga was the only one who saw she was being taken and the other Saints were convinced that the fake athena was the real one and Kouga went because he had a little bit of hope that she was at the Sanctuary.
The original series showed a Silver Saint for Cerberus, that hasn't been used in centuries, and Athena, as the Goddess of War as in "fighting smart", is known to have lied even to her own Saints and to have Saints especially skilled in deception (Hyoga in the manga is introduced lying his ass about his actual loyalties, Shun hid that he had achieved the Seventh Sense during training until he actually needed it, the Altar Silver Saint's main job is to be a Body Double, and so on)-it would be perfectly in-character for Kiki to lie about how many Saints there are, or even for Athena to do so, in order to hit an enemy with an attack from Saints they don't know exist.
In the canon series, Deathmask ended up losing his cloth because he choose to embrace his evil and sadistic tendencies. Schiller is a messed up sadist even for the average Mars' followers standards, yet he keeps his cloth. By the Saint Seiya Encyclopedia, we know that not only the Cloths are alive, but they get their sense of justice from the embers of their past owners personalities. With Deathmask being the ultimate nihilist, it's possible the Cancer Cloth itself simply stopped caring about what its user would do with its powers, satisfied he's enforcing his strength.
Considering the change from actual Cloths to Clothstones, one could assume that the limited consciousness of the cloths was reduced or outright removed.
◊ Some have attempted to justify this by saying that Omega takes many liberties with Kurumada's canon, and also makes use of inactive constellations. However, in episode 52, Kiki himself confirms that Athena's saints only count the 88 main constellations, and Geki in episode 53 refers to the Palestra students as Saint apprentices as opposed to actual Saints, making this argument invalid.
