The Rabid Gerbil likes this idea a lot. Having the chance at rerolling once or twice in a game seems just right.
As long as they remain "weak" in someway... as in vounerable to attack.
If you have the ability check out Warmachine rules for the proletorite (sorry can't spell it) They have these kind of figures that enhance others and might give you more ideas.
IDEA? To keep them fairly in play (an not safely hidden in cover in a corner) maybe their range of effect of friendly models needs to be kept to 12" ?