I think I’ve figured out how the
light power level works on drops.
First, this is all about “regular” drops. Whether common, uncommon, rare, or legendary (white, green, blue, purple), I just mean the ones that will pop up frequently through normal play or be given from vendors for normal stuff like turning in faction tokens. So I’m not talking about “Powerful Gear” rewards for milestones like Call to Arms (Crucible) or Flashpoint (Weekly public event bonus).
Regular drops seem to have a floor and a ceiling which eventually collapse into a single value. The floor seems to be a percentage, approximately 96.5% of your current maximum power. You’ll never get regular drops lower than that.
The ceiling starts out somewhere above your maximum power, and I don’t even have a ballpark figure for what it is to start, or if it’s a flat value or a percentage, but the ceiling seems to have a hard maximum of 265, until that would be lower than your floor.
So during the campaign and for a while after reaching level 20, you’re finding a range of drops, but even the stuff you’re coming across in the wild is slowly bumping you up. When you’re 240 you might find pieces around 243 or 246 or whatever, slowly increasing your maximum power level, in turn slowly increasing the drops. But once you start getting drops and vendor packages at 265, the value stops going up until your floor catches up. So at 260 you might start seeing 265 drops, then 264 you’re still only seeing 265, then you’re above 265 and you’re still only getting drops at 265.
From then forward, you’re only* getting drops above your current maximum power level from things like those weekly Powerful Gear rewards or Exotics. Once you hit about 273, your floor is 265 (the approximately 96.5% figure), and from there your drops will start slowly increasing again as your power level continues to increase, it’s just that from now on they’ll always be below your current max power instead of above your current max power. My maximum power now is 294, my vendor rewards and random drops are 284.
*As @baren mentions, mods can make a regular drop 5 higher than your current ceiling/floor, I’ll dedicate another rambling post to those.