Bingowings said:

I don't know if any of this is doable but (as well as dreaming about Padme) Anakin could have nightmares about his killing Dooku (proving he does feel guilt about killing an unarmed prisoner).

When Anakin enters the Mace/Palpatine duel what about not showing Anakin the Sith lightning (so he sees Palpatine as an unarmed prisoner like Dooku was)?

Mace brings his saber down and is blocked by Anakin's (as in ROTJ) and they have their conversation about ethics of killing Palpatine while Anakin and Mace are caught in a physical struggle (which mirrors the struggle of their polarised arguement).

Here Anakin is seeing a Jedi Master (someone who claims to be better than he is) about to do something he has himself done but has been racked with guilt about.

Is Mace any better than he is?

He also needs Palpatine to explain what he means about saving Padme as all Yoda can offer him is 'don't be too attached'.

If Palpatine is correct about the Jedi not being any better than the Sith he might be right about saving Padme too.

It adds validity to Palpatine's line if Mace has no problem with cutting down an unarmed prisoner.

When Mace is clearly not budging Anakin cuts off Mace's hand thus (in his mind) leveling the playing field as Mace has lost the ethical argument (from Anakin's point of view).

Then have Palpatine pull out the Force Lightning at the last moment by which time Anakin is so deep in the do-do that he can't see a way back.

That could be interesting.