From WotC_Mearls (D&D Lead Designer)The hexblade suffers a little because he came on the scene relatively early in 3.5's life. As R&D pushes the boundaries of the game, we learn that some things we thought were risky or potentially broken aren't. Other times, we learn things that look fine don't actually work in play.

Armored mages fall into the first category. Them seem really powerful, but in the long run they aren't. Spells and magic items allow an unarmored mage to build great defenses. The spell mage armor is as good as medium armor, and its duration allows most mages to keep it active at all times. If you compare the hexblade to the duskblade from PH 2, you can see how the thinking has changed.

If you want to boost the hexblade, I'd try the following changes:

Good Fortitude save Curse ability usable 1 + the hexblade's Cha modifier per day Curse ability usable as a swift action Curse ability does not count as used if the target makes his saving throw Ability to cast in light or medium armor and while carrying a light shield or buckler At 6th level, the hexblade can cast one hexblade spell per day as a swift action, as

long as its original casting time is a standard action or faster. He gains an additional use of this power at levels 8, 11, 14, and 18.

The key to the hexblade is his curse ability, but it's a little un-fun to have it so limited in use. The hexblade also has trouble casting spells and using his melee attacks, so shifting spells to swift actions fits in with the idea of an armored mage