I thought it was more of 'when dracula died for good, along with the castle most of his dark powers were sealed inside the eclipse in a form of chaos.'
The remaining powers spread across the world in the moment Drac died and the newborns got some of those. And once the castle resurfaced in 2035 their powers activated fully, like Graham's.
I seem to remember Dario's powers weren't anywhere close to what he had in dos before he actually met with Celia and Dmitri after the 2035 event. Dunno where did I read that though, perhaps some character bio.