To add to what GrundleBeans said, these rewards drop based on your overall power level, and it does not take into account the item with the highest power in the slot it drops in. So if your overall power is 1050 but you have gauntlets at 1051, and your +2 reward drops gauntlets, they'll drop at 1052 because that's 2 higher than your overall power. In this same example, a +1 pinnacle would drop at 1051, even if it was another pair of gauntlets.

Hi there. Vanguard/Crucible/Gambit playlist challenges provide +1 pinnacle rewards. You get +2 pinnacles from the weekly Means to an End quest, 100k+ score Nightfall: The Ordeal, Master Nightmare Hunt, Garden of Salvation, the Prophecy and Pit of Heresy dungeons, Iron Banner, and Trials.