I've thought a little more about it ...
DEX seems to be more useful PvE, while END more useful in PvP.
DEX adds evasion and aim, which is useful especially if you're going against red mobs or bosses.
END just adds general hp and def, which is good in PvP because most of the people you'll be facing uses normal attacks.
Am I right? :3
I'll probably go add DEX. Nobody wants to party me~ ;____;