If they want it to be really useful, it should provide significantly more mana regen per tick than it currently does. That way it would actually serve a purpose in prog settings. As it is, you could meld full piety over your whole set and you'll get like.. 2 more revives out over the course of a fight before going out of mana, it's a bad joke.
Or, as others said, give it the Tenacity treatment and make it roughly similar to Determination on a -10 ilvl piece, but I think buffing it to serve a niche purpose would be more interesting, because you're still never gonna meld Tenacity, and you wouldn't meld Piety either if it got this treatment.
