If it has to be nerfed in order to allow an increase for its reliability, then I suggest having Eclipse be an effect that builds up over time based on the strength of nearby light/darkness sources, and to get the full effect of the ability, you should have to absorb and maintain both at least a little continually. Add a visual on the frame itself where she's radiant around the edges when she's absorbed a lot of light and darker at the core when she's absorbed dark (you know, like an Eclipse) + a visual for when you're drawing in particles of dark/light from your surroundings (and stop when it's full), and viola, visual clarity.
As for how it operates as an ability, augment, and as an infused ability, I would really like for it to be a channeled ability with the light/dark resources decaying over time (scaled inversely with duration), have Total Eclipse allow people to absorb particles while they're in range (and have them decay when they're out of range), and as an infused ability decrease the decay rate so non-Mirage users don't get nearly as much of the combined/peak benefit as Mirage herself does.
I think making the ability more reliable is the most important thing, but it definitely could use some cool/unique factor added to it too, if it's getting a soft rework like this. Anything that does both of these is fine in my book.