Renew Item seems to be almost outrageously broken. I really like almost every change and addition you've made to the class, but once you hit 20th level you're handing out the equivalent of at-will Wizard spellcasting of whatever spells the Warlock can buy/find in Wands or Staffs.

On thing you really should do is come up with some new invocations (and probably shapes and essences) geared toward the various heritages, because as of right now half or more of the WotC ones are appropriate only for Demonic or Infernal Heritage.