NED uniform and Incendicus horns are proof enough ....
Joke apart, I just wanted to share my finding after 10 hours farming, for those who are interested.
In fact there is one "head decoration" per ennemy faction.
You just need to kill 34 000 ennemies of the faction (there is a success for each).
To increase the value of the farming, i choose a run where i can get SS rank easily (in order to aim for the 1000 SS rank title at the same time)
Took me 8-10 hours and around 200 runs (i didn't count exactly).
