You need to find armor with higher light levels. If you do the Prison of elders lvl 32 once per week you'll get an armor core, used to buy max armor from Variks in the reef. PoE 34 will give you Etheric Light used to max another legendary armor you already own. You can possibly get Etheric light from random rewards in the weekly nightfall. Etheric light can be purchased from reaching rank 3 and 5 in Iron Banner too.