I'm curious to know how the Darksaber is going to help Moff Gideon in any way. Don't get me wrong, it's cool. I was geeking out when Gideon cut himself out of the TIE wreckage with the Darksaber, and sure, Jedi and Sith use these weapons to great effect, but that's due in large part to the force and their abilities.
AFAIK, Gideon doesn't have any of these abilities and while he may be an expert swordsman (we don't even know that yet), Mando has blasters, a flamethrower, a jetpack and Beskar steel, which should be able to deflect a blow or two from the darksaber. If it comes to a close range, mano-y-mano fight, Gideon's way out of his league.
I'm think S2 will end with Mando beating the snot out of Gideon and taking the Darksaber as his own.
If I recall correctly the darksaber has a lot of symbolic value to it for the Mandalorians. Again, IIRC, according to tradition, he or she who wields the blade has a claim on leadership over the Mandalorians.