Dear Marcus,
Y'know this *might* not be impossible, although it could be a lot of work. Depends upon how much fine detail there is in the face. But I've had to tackle a similar problem doing restorations on mildew-attacked slides-- mildew produces a web of dark filaments that overlay the image. ASSUMING the face is everywhere lighter than the veil, it's a similar problem.
The approach I'd take would be to apply a low-pass filter to the face. "Dust and scratches" is a possibility, so is "median". Even "unsharp masking." Experiment! Then select that state for the history brush and revert to the previous state. Now paint over the veil using the history brush set to LIGHTEN mode. You'll be able to partially remove the veil without much affecting the face.
The trick is to make repeated passes at the problem-- filter, brush, filter brush. Try not to use too aggressive a filter on each pass. Don't expect 100% (or even 50%) removal of the veil on a single pass. Each filter-brush cycle, you'll lighten the veil threads a bit more and bring them into a closer match to the surrounding skin tones.
This very likely will NOT do a perfect job, but it may get you close enough (and remove enough of the fine veil structure) that you can use more conventional tools to clean out the last of it.
Note that this will only work where the veil isn't masking fine detail. If it crosses over an eye, for example, the filters aren't going to distinguish between eyelashes and eyebrow hairs and veil threads. So you gotta be REAL careful with that history brush.
And, if it ain't obvious, do this stuff on layers, so you've still got the original image intact.
Hope this helps some. Good luck!
pax / Ctein
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