Right now, Avatar's Favor is a mess of JA. It encourages passive play for the SMN and gives underwhelming bonuses that disappear every time the smn does anything. I think its easy to see what the dev's were trying to do with it way back when, but it needs some adjusting.
Here's what I think should be done to keep it in line with today's ffxi:
Popping Avatar's Favor should :
-Significantly increase aura potency of all avatars, except Diablolos' Refresh.
-No longer reset aura potency on use of BP:Ward
-Decrease recast time of BP:Wards by 50%, increase recast time of BP: Rage by 100%
-Increase potency on all wards, while increasing the flat bonuses significantly (Ecliptic Howl giving up to +30 max stats during good moon phase, Noctoshield giving -40 dmg taken per hit, -enspells and frost/shock armor granting significantly increased dmg per hit)
-Increase TP Bonus for healing BP's significantly, allowing Carby to heal up to ~1500 per aoe heal with 300% tp. Obviously this is to encourage use of Mana Cede, another underused SMN JA, and will make the two abilities work hand in hand.
-Increase intelligence of Light Spirit, making it able to cast much faster and react quicker.
This gives a reason to actually use the ability outside of extremely niche situations, and can make smn a competent support and healer class, able to compete with SCH or RDM, but not quite at BRD/COR levels, given their versatile nature. They won't be replacing white mages, nor will they be stepping on toes of other dedicated supports, but it will definitely make them a lot more viable in end game party situations where they really struggle right now.