Hello! are you COF or MG? It will depend on what you are to get the items, if MG just need gold and go to bazzar and buy items. I have gold for sale if you need some.
if you in COF, I'm not as familiar with profecies, but you get them to get items to drop, so if you want shields or scepters to drop you buy those and it will increase chance of getting it.
For the Abberoths command - Harbinger of Defilement (Fall of the Outcasts Timeline, empowered only) you need to farm this harbinger over and over until you get drop.
Reyahs light shield drops randomly, you can try using the acendency rune as well on any shield that you find and farm the monolith that drops the shilds as reward to increase the chances.
hopefully that helps, if not just reach out