I'll try to keep it short.
Flaws:

• Golem death animation.
  
• Upheaval animation screwing the book up.
  
• The handle of the lantern remains and the book is held in an odd manner. This is very apparent during the Upheaval animation, looks kind of silly to sway your Grimoire to chant a spell.
  
• The old icons do not go well with your new icons.
  
• The staff alone seems quite plain. Isn't it suppose to have a fireball on top of it?

Suggestions:

• Golem exploding animation? Like how Invoker dies. Or if you remember how WC3 Golems die, that could work as well.
  
• If his book is moved in front of his hand (roughly the same as the current) and the book "glows" in some manner during Upheaval that could work.
  
• His current book holding posture should be changed in such a manner that he's levitating the book up with his hand from below.
  
• Update those icons as well, I am sorry I can't give much feedback on that.
  
• It'd be great if the attack particles or anmation can be customed as well.

On the plus side though:

• The battle armor for a Warlock is executed perfectly.
  
• Having a hat and beard rather than his standard hoodie turns him into a real badass.
  
• The concept of the floating Grimoire rather than him holding the lantern is definitely refreshing.

Although this is a great set, I doubt that it'll get implemented if all of my suggested changes are done as it'd turn this into an Arcana worthy item and Volvo does not seem to make community made items into Arcanas. I hope though that it will get through.