In looking over the warlock, I like a lot of what it has, but feel the XP requirement is far too high. It’s very full on flavor, which is good. But it feels like a mage can do everything it can, and better, barring Hex & summon infernal creatures. Taking longer to achieve necromancy is possibly the biggest problem I have (level 13?!) with it. As it stands now, it’d be almost for flavor only if you wanted to make a necromancer as a warlock rather than a mage.
My take on the warlock is that he’s an impudent bastard that wants to bend the world to his will. Skeletons and zombies don’t have a will, they are at best tools available to the warlock. And maybe not very good tools. Empty graves and smelly corpses strolling about bring torches and pitchforks to the warlock’s door. The warlock is interested in necromancies other than raising and commanding undead. The innate powers you mention and similar spells are his bread and butter. A successful warlock is a secretive warlock. At least that’s how I see it.
A mage or arcane and/or divine custom class would be a better pure necromancer.