I personally don't like the RB heavens justice since it has a very long cool down which can be canceled anytime plus it doesn't hit as much unless you are inside the mob. I regret putting points into it, I currently have it as level 5 and gave up putting points into it, I would keep it to 1 for flinching purposes. Also, I didn't put points into calling thunder because of the lack of shots that it gives compare to the RB one plus the 40 second cool-down.
Well this is what I would like to have if I have skill resets:
The only thing that is different from my current one is that I don't have mp increase, I have max rage instead of 4 (black pearls are expensive but if I am really rich I wouldn't mind maxing it, besides the other two reagents are easier to farm from the history side-stages 5-10 and 6-10).
If you are wondering why I have a max normal wind scattering is because I use it when I'm inside the mobs where I can hit them all or when I'm touching all of them. I don't know if that make sense to others but yea.
By the way, max rb heavens will do 3-4k dmg per hit once you get 2k+ str. I just based this on my yuki's ice bomb when I have 2k str.
Hopefully this helps you a bit.