Honestly I find it surprising the explosion of the Cueball only damaged her eye and arm. For something so powerful, that was a pretty small explosion. Even then, it probably would have wrecked the entire lefts side of her torso and face.

Well, this is First Guardian powers we’re talking about. Scratch could’ve likely nuked the entirety of Vriska’s Hive if he wanted, but he didn’t want to kill her- Just punish her, and in turn, pit her against Terezi to fuel their feud. If anything, the fact he inflicted a wound that paralleled that of Mindfang’s when she faced Redglare is most likely intentional on his part, to feed into the Karmic Fate passed down by their Ancestors.