How to houserule exorcisms

[Heliomance]

I'm currently making my own setting, and as it's largely based on real-world myths and legends, I want Clerics to be able to exorcise outsiders as standard. The thing is, while any old clergyman with a strong enough faith can deal with a lemure, something like a pit fiend or balrog* is much tougher. How do I let clerics "turn outsiders" without trivialising outsiders as an opponent?

*Yes, if I use them, they'll be called balrogs. Balor is the Celtic one-eyed god of death and destruction. If the party fetch up against him, they're screwed.

[Snake-Aes]

Sacred exorcists can exorcise by default, if you have access to Complete Divine. It is basically a level check against the outsider's HD.

[Kaww]

Checkout Apostle of peace.

To not trivialize outsiders give them turn resistance as you see fit.