I really like the idea of giving mirage the ability to make zones of light/shadow to give her more control without buffing the helminth but instead of having them randomly made by eclipse have it instead be made by slight of hand, make slight of hand tap/hold and make a radius of light/shadow at the cast point as i feel it would fit the ability better, it would give her better control without buffing the helminth while also give mirage some better ability synergy then the little grenades that dont do much.
But on top of that i think eclipse should have its minimum buffs increased as right now being able to only get a 1% damage/defense buff can make the ability very inconsistent, increasing the minimum buff to something like 25% damage/defense would make the buff more reliable without breaking it.
Something else you could do is give the player a reduced version of the opposite buff so while the player has a 200% damage buff they would still receive a 25% damage reduction buff and while the the player is at 75% damage reduction they still get a 50% damage buff, this would make the ability more reliable and players would be more likely to use the defense buff as right now most players exclusively use the damage buff, though admittedly this might be better suited for an augment mod as it might be a bit much for the base ability.