I think I'm really stumped here. I've got some knight's armor installed which I'd like for one of my followers. Trouble is one of the ingredients for all pieces are "Magic Ore Ingots", which you can only get by somehow getting hold of, yep, you guessed it, "Magic Ore"! Trouble is I've never heard of Magic Ore being available in any way in Skyrim. Anyone got any ideas how I'm supposed to get hold of such a thing? Do I have to make it via alchemy or what?

Whatever mod added the "knights armor" most likely added the "magic ore" too.
Ask the author about it if the information isn't in the readme (assuming the author even included one).