I skimmed very, very lightly, so I apologize if this isn't entirely relevant;
1. Gauntlet hades with meter is his strongest, and kind of only, tool. Block it and let him burn the meter, if you have your own meter block it and post rapid, next possible point counter assault.
2. Without IB, you will never beat Ragna. Don't even consider it. If you really, really suck at IB, you can try using Barrier sporadically, but honestly the only real advice I can give you is get better at IB. Still, use barrier as well. It will help.
3. Bang's AA's are useful, but only to beat out certain spacings. Trying to beat his full spaced jC is suicide (If you see it coming late, jump IB punch him afterwards), trying to beat jB is generally suicide (Same deal for this one, or jump back to avoid it)
4. You can easily stagger against Ragna. If his DP is hitting you every time, you're messing up, bad. You need to add in spots that OS beat his DP, like a 2A meatied on his wakeup with proper spacing. You should never burst Ragna's DP, it's a very low damage starter unless CH AA. I am going to guess that your mix up is too stale, and you aren't using enough move variety, that's why he can easily DP you. Mix it up bro, I guess. Bang has a decent advantage in this matchup.