I got it and it extend the lenght of warcry by 10 seconds, even if you put it on, use warcry and then put another head piece on, so definitely good with an equip switching macro.
lol, actually your kinda right but kinda wrong. Drks AF2 helm says "Enhances Souleater" or some job ability of theres, but it just decreases the def you lose (so whichever ja drk loses def, that's the ja I'm talking about) not the attack gained.