The double black for whip of erebos might be a problem

I really don't like Whip of Erebos here. The best reason to splash black in white weenies is for Xathrid Necromancer, which helps against board wipes. Otherwise, I think the whip is way too clunky to use effectively. I would say go mono-white and replace the whip with Heliod, or else splash blue for Ephara.

I agree about the concerns for whip. To address Xathrid Necromancer , I was considering him except that the strong cards for white weenie are not humans.

I was debating about splashing blue for Ephara, God of the Polis since it will also allow me to use Azorius Charm and put Detention Sphere on sideboard (sorry it is one of my favorite cards).

I will probably be debating between mono-white and Azorius colors since I do not really like Boros or Selesnia in standard right now. (Bosor doesn't work in my local scene unless mainly white-weenie and I don't have Voice)

I think adding Detention Spheres and Azorius Charm is a great idea, and Ephara will give you great card advantage.