More serious i have i think a not too bad idea :
Vynd's and Jack Simth's suggestions are very nice but iirc not doable with the current modding commands .
So my new suggestion : It seems you can't mod a weapon yet to triple damage vs undead e.g.
.
So give them as Zen said higher attack rating but instead a herald lance as built in weapon and a bit higher hp .
My unblessed new angel would look then like the following :
Weapon herald lance ,total attack of 17-20 , total defence at 12-13 , hp 25 - 30 .
This way he would hit a devil with 16 defense with 54,8% with 17 attack , with 79,7% with 20 attack .
Then the herald lance would result in 19 x 3 + 2d6 oe damage vs. 8 protection +2d6 oe from the devil .
Voila , a dead devil . If you run a quickness blessing the angel should be quite horrible against devils and without he would still kill normally 1-2 devils before he dies because with 25 - 30 hp he should survive one devil at least .
With the herald lance he would not do much damage against normal troops though so normal troops would be a counter to angels while the angel would be a counter to devils and finally the circle is closed with devils as a good counter to normal troops .
The biggest problem is though that you get 6 angels + 1 leader for 50 astral while you will have normally way higher numbers of devils/FoDs as opponents .
100 pearls = 250 blood via wish and soul contract is very popular so i think normally a typical encounter is 1 angel vs 3-4 devils .
If you alter the defence of the angel though then he gets way too good against normal troops as Huzurdaddi says and this should be avoided .
Perhaps Awe should be removed and replaced by something more useful against devils .
Really hard to make them fit because you have to keep in mind that they can get blessed and if their defense is too high together with awe they will rock normal troops as well .