1. In this last episode, Din tells Bo-Katan that he doesn't really know anything about the Darksaber and that it means nothing to his people, and that he'd follow her for reasons of honor, etc. instead. Din was raised in that covert, so if the Darksaber doesn't really mean anything to "his people," it doesn't really make sense that most of them would bounce as soon as they saw Gideon with the Darksaber.

2. We don't know who (or what) was in those new model beskar Stormtrooper kits Gideon unleashed on the Mandos, but they were pretty much cannon fodder until the Praetorian Guards showed up. In fact, it's shown that the Mandos were able to beat them by immediately knowing the weak spots in the armor (like the gap between the chest and back armor and the helmet) and hitting them there. They didn't seem to fight the Mandalorians on equal footing at all, which you would think another group of Mandos would do.