As I don't see it in the list, I'll put it forward: A self contained equipment/item editor.

After fiddling with the EE Editor, with the help of Baardvark and SniperHF, I've come to want an item editor that is built into the game editor. I've seen item editors in editors for games like Dragon Age Origins or Elder scrolls games and used them with little effort.
Understanding how to add a custom item in DOS:EE was less straightforward, what with most of the editing being done outside the editor.

Unless otherwise specified, just an opinion or simple curiosity.