Some of the things I have to mention is why keep dual blast with two rays instead of trying to assimilate it to BAB, at least allowing an 8th - 10th level or higher to shoot two bolts and a 15th-20th level character to shoot three. Two blasts seems a bit shorthanded by 15th level, even if they get full blast damage, especially as a full round action. Eldritch Glaive, Hideous Blow and the Eldritch Claws feat may act separately, and won't be affected by the Dual Blast ability, unless I'm missing something.
Another is how you've worked the Warlock to be based on ancestry, but how Imbue Item and Renew Item seem to be a bit off (even if part of the original class). I would suggest delving a bit closer to Deceive Item rather than to Imbue Item, out of fitting the flavor of a caster a bit better. A capstone that grants a, say, +2 increase to the CL of any item you wield would be decent, since it could make high level spells work almost at full power and make lower level spells work slightly better. I know Deceive Item and Imbue Item are meant to be related, but Imbue Item seems to be the craft of the Artificer (pun intended) than the craft of the Warlock. The Warlock works great as a deceiver, but not exactly as a crafter.