Shadow Hearts: Covenant is basically the type of game you're describing. It's a fantastic game and easily one of the best RPGs on the PS2. It's generally recommended to be familiar with its predecessor (either by reading a plot summary or playing it) for full enjoyment of the sequel's story, which sometimes turns people off, as the first game is pretty average. However, you really are missing out on something awesome by not playing SH:C.

Btw, Tales of the Abyss is a standalone title and would be also be a pretty good choice.