She picked up a crystal off of oryx's sword. If you look closely it's the same crystal as the one on top of the hilt on your swords. And who gives you the quest to create your sword? Eris is not evil and I don't know why so many people are confused on this topic. I still see posts saying "IS ERIS EVIL?!?!!??!?!" Edit: since alot of people are ignorant and dont want to believe me here is something to add on. Mara sov in the opening cutscene for ttk says "you and I both know how this ends ever since you crawled out of that pit" Mara sov is a queen and Eris is the only one that came out of a pit. Mara also refers to eris as an agent of some sort and eris is part of ikora rey's secret order of warlocks *CORRECTION* secret order of Guardians *sorry*. [spoiler]just wanted to clear that up[/spoiler] Ill just wait for some more hate down below to prove me wrong. Or well attempt to. Edit: The point of this post was that I don't think Eris should jump to conclusions saying Eris is evil from that ending after we defeat oryx. I've seen people say that she has connections to some other hive God which might be true I haven't gotten too far into reaching the book of sorrows yet but i was just clearing up the ending seen where people claim Eris picked up some evil hive crystal from willbreaker (oryx's sword) to try and kill us Edit: 350 replies. Some agreeing with me. Some strongly disagreeing and others that somewhat agree but are telling me some more of the lore from the book of sorrows (which I am yet to have read)[spoiler]dont crucify me for not reading the book of sorrows please[/spoiler] Edit: to those who don't think Eris was talking to Mara sov, in the grimoire card for "The Road To Kings Fall" Eris says "Mara sov was right, it is all down to the guardians now"