ChickenNugz

The biggest mistake I see people make in RD hard mode is using units in part 1 that will not benefit you in the much harder Dawn Brigade chapters in part 3. Units like tormod, nailah, vika and maurim will not be available in part 3 (they won't be around again until part 4 at the earliest), so they shouldn't be used at all, except when absolutely necessary. Other units that you shouldn't give a single kill towards if you can avoid it are the Black Knight (except in 1-9 of course) and Sothe. Sothe is a horrible unit and his only use is being unequipped and tanking hits early on or getting you out of a sticky situation. He is garbage in part 3 and later cause his growths are really bad. If you focus on giving most of your kills to Edward, Nolan, and Jill you will find the part 3 DB chapter's much easier and you'll have useful units for part 4 and the endgame. Edward will take a little bit of babying but it'll be more than worth it later on. Hard mode in RD is all about experience management in my opinion.

I gotta say I love part 4. So many different team combinations you can use and lots of unique battles. But I really enjoy a challenge so maybe that's part of it, I only enjoy playing on hard mode. I did want to mention that I love using bexp on Jill and Edward. Jill can get RNG screwed sometimes but at other times she becomes the best freaking unit in the game (outside of Ike of course. So OP!). I have found the RD chapters in hard mode to be MUCH more manageable when I focus on Edward, and even more so when I pair him with nolan. Edward's growths are really good, and anything he is lacking can be made up with a bit of bexp once he's capped SK, SP, and Health. By the time you get to the endgame he'll have capped all his stats outside of MAG and RES.