, well you say what people know and what they already ask.
Undead Dragons have the qualities similar to that of Nito: Toxicity and A Skeletal-Like Corpse. The Undead Dragons are of simialr form as of those of Skeletons instead of Hollows.
The reason the Tooth and Fist of Dragons does not have much in ways of a special power, is because they do not come from the tail... the tail being the spine extending from the back, connecting to the brain. If you look at sorceries, which use the power of the soul, they derive their power from intelligence. That means that the soul, the essence, of the being is extended to the tail. The only exception is Priscilla, but of course she is not a full dragon.
Last, but not least, the beings with dragon scales, such as the drakes and hydra, seem to show similar qualities of animals. Other dragon creatures, such as the Basilisks, Mushroom men, Crystal lizards, Man-Eater Clams, and the Tree Lizards are seen with similar qualities as such dragonoid creatures, and such creatures seem more animal-like than the actual dragons.
I don't agree with much of the lore sentiment, but of course "that's just me". I hope to see more of your videos.
As for Nito and the undead dragons, if you look at the skeleton bodies (not the living ones) in the tomb of giants, they are of similar quality as the skull in Ash lake in their head. As well, the one is the Painted World as contains creatures of undead, the Bonewheels, and Lsot izalith is just near-sighted from the Tomb of Giants, in which people can see from their. I have already speculated that the valley leads towards the Demon Ruins/Lost Izalith, which is why the halberd black knight, a chaos hunter, resides near there.