10 + 1/2 Hexblade level + Cha modifier isn't as hot as it sounds vs. a Will save, if I have to be honest. If you're using this class, you're going to have to split between your Charisma and your melee stat; Whether that's Dex or STR, that's up to you. Dirge of Woes is only really good against Good characters due to the high DC being, around max level, 30+. The DC for Hexblade at level 20, will be on average between 23-25 for your primary class ability, or 25-27 if you've taken the feat to empower it. Rogues, Barbarians, and Fighters can all achieve about 25 Will with universal save items and enchanting by late game, which means this ability has limited use, applies unreliably, and can only be fired off once per round. Unlike Paladins, however, Hexblades do not get spells that compensate for their stat-splitting that boosts the values, like Aura of Glory, for instance. If you invest heavily in Charisma to try to increase the odds of this ability being useful, you're making yourself ineffectual in combat, even though the payoff could be high.
I'm not saying it's utter trash, but it's not going to become part of the PvP meta of the server that way. We're looking at what is, essentially, a Fighter with fewer feats and some mediocre spell variety, with an unreliable class ability in a PvP environment with the 2 + INT Skillpoints. Compare this to Bard, which has a 3/4 AB progression, but can use Bardsong and Cursesong in the same round, without a save, up to 25 times at max level throughout a combat, or can use a number of songs simultaneously in quick succession if they've invested in Dirge of Woes/etc as well utilizing Subsonics. Hexblades with an Empowered Curse can achieve -7 to the enemy's AB, a Bard can achieve +4 AC and -3 to the enemy's AB achieving similar effects, but the bard's AB is lower from the outset by about 4 points. Admittedly, the Hexblade debuff is stronger overall because Hexblades have a higher AB to begin with (so the -7 to their AC will REALLY hurt) but it's not reliable in a PvP setting. PvE, perhaps, however.
I wouldn't compare this to Bard. It's Bard-like, maybe, but I wouldn't pretend that Hexblade is going to redefine the PvP meta in any significant fashion unless it ganks someone who isn't wearing their enchanted equipment at the time; But that's game over for just about anyone, getting ganked. It be a gank eat gank world out there.