Blood

The difference was that Demons and Titans still mainly followed the body path. While Demonic Royals also placed emphasis on the body, they branched outward to comprehend something Dyon hadn't heard of in a long time: Martial Intents. 

[Author's Note: Martial Intents were first mentioned in chapters titled 'Martial Intent'. Haven't been mentioned since. Though, it should be noted that Ri partially touched upon its realm back then.]

That said, Dyon wasn't unfamiliar to with Martial Intents. For example, Faith Seeds were kernels of martial intents. What made Higher Existences who could begin to form them so special was that their intents were so powerful that it could manifest into reality and even be passed on should they transcend. 

When techniques decline with the passage of time and the weakening of a clan's Faith, it's precisely because that technique's Martial Intent has weakened. Or, rather, Faith is no longer able to protect it from being forgotten.