The devs have stated this is a Jedi game, not a sith game, you will not have any dark side powers. Now as for red sabers, we really don't know, there are chests to be found in the game that will have cosmetic items for your character, light saber, BD1, and the ship. Who knows if we find some Sith relics.
The reason fans were upset about Fallen Order not featuring dismemberment is that it defies the logic of lightsabers themselves. Being "light swords," the weapons slice through anything like butter, and the series has long shown limbs being cut off. As IGN explained in an IGN Now video, the ultimate reason behind the lack of dismemberment wasHighlighting the new content update is a New Game+ mode, allowing fans to replay Fallen Order with previously unlocked cosmetics, including lightsaber crystals. New Game+ players will get an