When you're in the level 20+ realm, the progress bar shows how much Light you're away from your next Light level. This can only be increased by getting gear with higher Light stats and/or upgrading your gear. With the gear with Light, your stats get boosted when you upgrade the pieces so definitely do that as well as keep hunting for better gear.Thanks for all the quick responses, everyone! One more question, as I'm about to become level 20:
So, I know for level 20 and up I get a higher level by getting better gear and/or weapons. So my question is: What does the progress bar for your represent when you need gear and weapons? Is it how much you've upgraded the gear and weapons you have?