[Rocket Man]

Some possibilities:

1) Buy time. Dominic only visits once a week; there could be as many as seven days before he comes around again. (Or better yet, have him visit early BEFORE Mr. Virtue has met the demons, meaning he's got a week of sitting anxiously on his hands before he can report anything.)

2) Keep the other players in the dark about who they're dealing with, too. There's at least a few cases where the PCs may well know they're dealing with celestials, but not with demons -- it's pretty much laid out in the setting that the "Austin clique" won't reveal too much to a new celestial until they can be sure of who they are and what their motives are.

3) If the veil begins to slip, see if one or two of your PCs are willing to help keep up the masquerade. (I know, you dismissed this in your OP, but it's worth trying.)

4) Keep that Malakite busy! If there's always a bigger evil to chase off after, he's not going to have time to worry about a few odd-seeming celestials.

5) Give him orders. A Malakite cannot let an evil live if it's his choice; however, Dominic plays subtle games for a Seraph. Perhaps he's commanded the Virtue to not strike without orders unless his life or another's is in danger, so as to make sure that he's acting with clear-eyed Judgment instead of responding to what may be a distraction by the enemy. (And since this is a mystery, this could work especially well ... he has to be the Archangel of Judgment's eyes in Austin, carefully peeling back the layers of deception until he reaches the truth, rather than simply going scorched-earth.)


Something else to consider -- the setting has been set up to be deliberately unstable. Judging by the intro, the PCs are meant to be something of a tipping point, upsetting the delicate balance that's been maintained for so long ... and making the setting into one that will truly be your own. So your biggest problem may not be as much of a problem as you think.