What about instead of just outright nerfing Prometheus Lens they did something different with it? For example; keep it at its current power level but give it a huge flaw. Maybe a seriously low ammo level (it's so powerful it depletes energy cells quickly). Or maybe you can only fire it in small bursts because it overheats and significantly damages the user when fired for too long? Maybe even a small explosion if it critically overheats (damaging both enemies and team mates). An overpowered exotic still but with serious consequences. I think that would be an interesting alternative to just quashing its power.