Kôkabîêl then is not just a demon or even a Baalseraph. The Baalseraph openly defied their Lords and were cast into Hell, the Grigori betrayed the trust of their lords and were cast out. While the differences between these groups can be somewhat academic at least the Grigori do not hate humankind.
Kôkabîêl is/was the angel of the stars and constellations. He taught men and women the secrets of astrology. He can provide a boon of good luck if he knows a person's birth date and time. This boon is a one time +4 on any one roll at a specific date and time.
He appears as a tall handsome man with dark skin and black wings. He wears loose, flowing robes of regal nature favoring whites, purples and deep blues. His head is bald and his eyes glow with star light.
Alignment: Lawful Evil
Movement: 120'/240' (flight)
Armor Class: -4
Hit Points (Hit Dice): 180 hp (26 HD)
Attacks: sword (x2)
Damage: 1d12/1d12 +flame
Special: +3 or better weapon to hit, immunity to fire, electricity and poison, regeneration (4 hp/round), see in darkness, magic resistance (75%), telepathy 250 ft., undead destruction
Like all Grigori Kôkabîêl has a sword of flame. He loathes to enter combat, but he is more than capable of it. Also like all Grigori he can invoke the remains of his angelic powers to destroy undead as cleric of 20th level.
There 20 Grigori that were cast out of Heaven. They seem most similar to the Baalseraph; both were agents of good, angels and now evil. But there is where the similarities end. Each Grigori commands 10 fallen Angels and any number of their own monstrous children, the Nephilim. Unlike the Baalseraph they are not bound to Hell and do not need to be summoned. They may roam any plane they choose, save for the upper planes they were removed from.
If you like Nephhilim then please check out Halls of the Nephilim!