The ability to filter your spoils trade ins by hiding your gearset items.

When you trade in items, EVERYTHING Diadem related will show up on your list, this includes items saved in gearsets. So if you aren't careful, you can potentially trade in your good 210 equipment with or without notice. I'm speaking from experience here too as I lost a 210 ring that was superior to my savage ring that way. You can argue that "I should've been more careful"(which is true, I should have), but an option like this can reduce future accidents regardless.