Neither Dragon Knight game is in anyway a port or related to the PSX Ryuki game other than using "Ryuki" (and thus Dragon Knight) as the stylistic basis of the characters/powers/enemies used and being under the "Fighting" game genre.
The DS game, from what I've heard is pretty different from the Wii title, as it is more focused on strategic gameplay than a straight up beat'em up: you can fight multiple characters on a stage; careful timing, use and, choice of Cards is crucial; and the game has no multiplayer feature as the characters level up after battles and get continually stronger and more difficult as the game goes on.
It was also made by a different design team (though still released by D3Publishing) than the Wii title/Climax Heroes.
So don't expect a PSX port, but the DS game is a different take on the concept from the Wii Dragon Knight. I can't speak from experience but you should probably give it a shot to see if you like it.
Though to be honest, why did people think they'd use the PSX game? It was a couple console generations ago (it was released around 2002-2003) and fixing the coding and performing an overhall of the game engine to 2009 standards would likely be much more expensive to do than just making something new, or using a more recently prefabricated engine (such as the Wii Climax Heroes engine). I mean I know it was a "Ryuki" game but I don't think that Bandai/Adness were ever that desperate.
In short, don't believe everything you hear on Youtube, especially if comes from the comments section.
