I've always wanted the feds in specifc, but anyone in general to have access to more stealth options- particularly non-cloak options. While cloak is really fun, I feel it's an overused mechanic. Mask Energy signature can be useful, but takes up a valuable sci slot and can't be activated during combat.
Enter the refractive shield, which would have a lowl shield cap and normal or lower regen- and as a tradeoff provide an always on passive +stealth boost of 1k-2k, which of course could be increased with the stealth skill, stealth boosting consoles, and would stack with other stealth stuff like mask energy signature, or cloaking devices. To balance stealthhax, this sort of stealth boost could decrease in effectiveness significantly when the ship with it is firing weapons. Sort of like a battle cloak, but much less effective and otherwise automatic.
A refractive shield as a shield type would be nice, or a one-off item, but it might work the best in some sort of 'covert operations' universal endgame set. Refractive shield for stealthy stuff, some sort of phase-shifted tachyon deflector (I just made those words up), which could provide a +% stealth boost, and say a 'shielded impulse drive' which would provide some sort of +% defense bonus a la the Aegis impulse engines, or some other not usually seen bonus- maybe an aux power boost... idk.
Set 2 bonus could be something like 'Phased Particle Sheath', which would be a +% all energy resist while moving (between low and high depending on speed), and maybe a passive boost to starship stealth.
Set 3 could be some sort of sensor overload/placate/engine boost ability to allow for escape from combat.
So like, you'd hit it, and your ship would release a pulse that would do an AoE 'jam sensors' style effect to all ships hit (allied too!) and do something like the impulse burst console effect.
So you'd fire off this pulse and rocket away while enemy ships are invisible to you on both sides, unless you resist the effect.- and even resisting it, the guy is still rocketing away.
An alternative that would require some developing but would be really cool would be to have say the set 2 or 3 bonus provide a %chance of activating a 'deflection matrix', which would deflect 'missed' energy attacks at the nearest enemy. Sort of like feedback pulse- so like, say a feddread shoots your klink with the phaser lance and misses- normally it lances out into space. In this case, it visually appears to hit the shield- and then a second phaser lance lances out from the shield to hit a closer enemy for like, half the damage you dealt.
Something else I'd love to see would be 'alternate set items'- so like take the Aegis set, and then release an "Aegis Resilient Shield" with different individual bonuses, but the same set bonuses as normal. Repeat for the other sets. Give some variety instead of the one true retro borg set :p