Chapter 2 grinding Someone mentioned Rafflesia and using Bomb Fragments I think?
Rafflesia are in Florem from Chapter 5 onwards.
However there are Alraune in the garden areas, which can appear in larger groups than other enemies. If you have powerful group attacks then they might be o.k. to grind against, until you can move on. (E.g. Crescent Moon.) ---
Should you get the Valkyrie asterisk, you can use powerful physical attacks with Crescent Moon. And yes, Lu Bu's Spear is perfect for that. The Alraunes (And to a lesser extent the other enemies in Florem Gardens) are defeatable after a couple braved Crescent Moons. You can even speed it up and put it on auto to really grind up that EXP!