I'm making a difference! Woo!
Two more:
Stalker (I'm pretty sure the idea of some "sneaky" trait has been presented several times. Let's see if my suggestion is any different to those):
Requires: 2 for Hellrunner
Enemies can't see you if there's anything bigger directly next to you, i.e. you'll be invisible to them if you're next to a wall, a barrel, or a monster - in the last case, though, the particular enemy can see you. If you attack an enemy or do anything hostile, they will be able to see you, until you either move or wait. Picking up items, reloading weapons, and such are allowed while remaining hidden.
Armorer:
Requires: 2 for Ironman, 1 for Tough as Nails
You can fix armors over time, i.e. they will regenerate, about as fast as your extra life decays while having Badass on the first level. Second level on this trait will increase the regeneration rate, as well as increase the general HP of all armors by 10%. Third level, while further speeding the regeneration, will also make it so that the armor will always give at least 1 armor point, no matter how damaged they are.