The Saint Avatars differ in strength entirely depending on the divine nature and power the deity is willing to invest.
Take Tiamat and Bahamut for example, their strongest Saint Avatars have a challenge level of 30, but the weakest ones are only on par with adult dragons.
Especially Tiamat's weaker avatars have a challenge level of only 13, specifically used to convey her holy intentions and enact evil revenge on those who thwart her schemes. She always travels with a large group of guards to protect and serve her, and has even had a companion among mortals, once giving birth to a half-dragon warrior.
Bahamut's situation is even more amusing; one of his avatars only has a challenge level of 12. Summoned by a pact from his believers in the otherworld, he was then dominated by an evil magician and sent to have good dragons attack human settlements, eventually enlisting the help of a trusting young silver dragon.
