[Dusk Eclipse]

If you are going for a more martial build, I can't help but suggest you to look into Suel Arcanamach (CArc), 5th level spells cha based casting, with an extremely sweet spell list (any wiz/sorc spell from the schools of Abjuration, Divination, Illusion and Transmutation IIRC).

Also I suggest the fighter dip, since most gishy prestige classes require proficiency with all weapons (including ranged) and/or proficiency with all armour types, on the same vein I discourage Barbarian since it's key feature (rage) doesn't mesh at all with casting

Edit: Hexblade 4 also gives access to the sweet sweet Dark Companion, which is a moving no-save debuff, if you are already going Hexblade there is no reason to skip dark companion since it is essentially free (even if you don't use save-or-x spells, which you most likely won't, your spellcasting companions will love you)