Back in vanilla there were ascendant shards and energy. Radiant shards and energy are the dark below expansion version. Back in vanilla and dark below, in order to upgrade legendaries to max light, you needed these materials which were pretty limited in supply. It was an absolute bastard to get max light gear not to mention only raid armour could even be brought up to max. House of wolves introduced etheric light which was a single item that would raise a piece of armour to max. Then TTK introduced infusion and the new light system which completely overhauled it and eliminated these materials. They aren't used for anything now unless you wanted to raise some gear from Crota's end to year 1 max (I don't even know if they're needed for that anymore). There should be someone that you can trade them to now though for some motes or something. I think Eris takes them. TL:DR. This was a very different game back in year 1. Just know that they are pretty well useless now and I'm pretty sure Eris will take them off your hands.