I ran across this while looking for something else: back in the day, I went ahead and converted the basic stats for celestials (angels and demons, basically) in GURPS In Nomine from 3rd to 4th edition. I also converted a bunch of Servitor Attunements and whatnot; I should collate them and put them up, too. Something to work on.
Basic Celestial [566 pt]
GURPS IN NOMINE (4th Edition conversion)
Attribute Modifiers: ST+4 ; DX+4 ; IQ+4 ; HT+4 
Secondary Characteristic Modifiers: None
Advantages: Alternate Form: Celestial ; Detect Symphonic Disturbance (Common) ; Doesn’t Eat/Drink ; Doesn’t Sleep ; Essence Control 9 ; Immunity (Disease) ; Language (varies) ; Non-Reciprocal Damage ; Power Investiture 9 ; Regeneration (Slow) ; Temperature Tolerance 5 (Cold) ; Temperature Tolerance 5 (Hot) ; Unaging (Can still appear to age, +0% feature) ; Very Fit (Doesn’t Fatigue Variant) 
Celestial Form: Advantages and modifiers as above, plus Doesn’t Breathe ; Insubstantial (Can carry up to No Encumbrance +10%; Costs 2 Essence to activate, -20%; Requires Will roll to activate, -10%; Causes Disturbance, -30%; total -50%) ; Invisible to Machines .
Disadvantages: Disturbs Symphony [-15]; Humble or Proud [-1]; Secret (Celestial) [-5]; Sterile .
This is the basic package for both angels and demons: it does not include Choir or Band resonances, nor does it take into account specific conditions (such as being Outcast or Renegade). Items in italics represent GURPS In Nomine-specific advantages. While technically the base form for an angel or demon would be his or her celestial form, most adventures will take place on the corporeal plane.
The base cost of Essence Control is , plus  for every level in it (including the first). The extra language known will be a human tongue; a celestial’s native language will be either Angelic or Helltongue. Non-Reciprocal Damage applies to the Alternate Form: damage taken while in celestial form will not affect the regular form, or vice versa. Power Investiture must be divided between Corporeal, Ethereal, and Celestial, with at least one level in each for Earth-bound celestials. Finally, “Disturbs Symphony” indicates that a celestial causing damage to persons or things, spending Essence, or performing Songs will be detectable via Detect Symphonic Disturbance.
The material presented here is my original creation, intended for use with the In Nomine and GURPS systems from Steve Jackson Games. This material is not official and is not endorsed by Steve Jackson Games.
In Nomine and GURPS are registered trademarks of Steve Jackson Games, and the art here is copyrighted by Steve Jackson Games. All rights are reserved by SJ Games. This material is used here in accordance with the SJ Games online policy.