@MaXS_0N no, charon absorbs kinetic energy (which would include bullets hitting him) but Hiwana shot him right as he was emitting his stored energy thus bypassing charons absorption barrier (which has been explained many times before)
Well it was pretty much the only way they could reasonably hurt Charon, trying to solo him is a giant waste of time since by the time you get his counterattack timing figured out you've taken too much damage.
And even after everything, the mass-murdering piece of shit only gets a hole in his side. He's still going to be alive at the end of the series, isn't he? Presumably without ever facing real consequences for his crimes. Disappointing.