At 200% is fine, without the toggle. The inconsistency and extra steps you have to take keep it in check, such as using an invisible frame to snapshot the buff and benefit from it even in dark areas. They said if eclipse is going to have a toggle will get nerfed so doesn't make sense to be left at 200% on mirage. For example, garuda's passive, primed chamber, and beguiling lantern also give a 100% multiplicative increase, similarly to eclipse. It also becoming 100% would be just fine.
Bad weapons are bad for a reason. Instead of buffing them massively just to make them viable, use better options. Just because someone wants to use bad weapons, doesn't mean eclipse staying at 200% on mirage is fine. I get people are attached to it and don't want a big nerf, but that's not objective.