Level advantage is limited. The way it used to be around the House of Wolves era was 7 levels. So if your Guardian was lvl-34 you would do more damage to a lvl-33, and progressively more until the 7 level cap. Your damage to a player 7 levels below you would be the same as a player 8 levels below you, or 10, or 20. The same was also true for PvE. On patrol as you got higher you would do more damage to the basic Dregs in the cosmodrome (for example) but once you reached 7 levels higher it would not increase any further. When the light levels jumped to the 300+ mark the level cap changed to 70 levels difference. God knows what it is now but I've no doubt its still there, and if it is around the 70 power level mark then a 540 guardian will recieve just as much damage from a 200 guardian as a 470 guardian. It keeps it fair that way. Ok? Got it? Good.