Firstly they could reveal that she lost in battle and to redeem herself she must win it back through honourable combat thereby explaining why Sabine could give it to her and Din can't?
I don't have a problem with the bad cg and the fight was a bit odd but not unusual given they were fighting a force user so Luke trained by Yoda to be able to shrug off the blaster bolts he doesn't block isn't a problem.
Now I'm imagining Din finds Boba and they talk about the Darksaber deciding to have an arm wrestling match for it so Din can tell Bo he has it now so Boba can teach the Princess just how wrong she is!