Actually, we don't know whether Vriska's death was just or heroic. It could have been just for the reason you mentioned, or heroic for letting Terezi do it and get closure, ect., by killing her.

Very true,

a better example would have been if when Jade was killed while she was grimbark and being menacing towards others that would have been a just death and she would not have come back.

~Mod T