[thejeff]

One problem with Oreiads is they're sacred but not priests. If you're relying on a bless you'll have to send some one along with them, probably on Bless/Bless/retreat. This raises logistical issues.

Without a bless, I'd try them without gear against indies. Air Shield/Resist lightning/Shockwave would be minimal. They'll probably die fairly often though. Using them in pairs will help.
Switch Air Shield for Mistform, add Stoneskin and they'll be solid. You'll want reinvig for longer fights. Summon Earthpower or Messenger Boots.

Luck is always a good addition. Against AI nations, add mr or elemental resistances as you expect to face them.