Is Arc Arena also available since it's technically an expansion of Arc the Lad 2?
Anyways. Best game on the PSN. If you don't own it, then get it. Also get Grandia. They're both awesome.
If you want to have access to the Romancing Stone item, and any hope of defeating the last boss on Arc the Lad 2, 0mp skills, not acquireable until atleast halfway into the game, you'll need to get the first Arc the Lad and get all four Romancing Stones, or download a save data that has all four Romancing Stones. He's seriously the hardest last boss in an RPG without it. Without it, you'll either have to grind a lot before facing him, or purchase Arc Arena and get some of the special monsters or special weapons included in that game only, and there's still the possibility you might have to grind, which Arc Arena also makes easier with the tournament mode and monster levels keep scaling the further you get.