I've seen this on older delrin-handled knives. It's especially noticeable on older Case Sod Busters with the black delrin, which really shows the grey haze. If I recall, some older knives had delrin or similar handles which would haze over because of chemicals leeching out from the scales and oxidizing. I think the implication was, if a knife was new, especially, to make sure it was able to 'breathe' or air out, to allow the chemicals to evaporate off before the scales get oxidized. In a way, similar to the 'outgassing' of old celluloid-scaled knives, but not nearly as damaging or dangerous (or corrosive to any metals nearby). I don't think this is an issue with newer versions of delrin, as I've only seen it on older knives. Old knives that were in 'new old stock' condition, and still wrapped in factory packaging, I think were most vulnerable.
You might be able to use some very fine wet/dry sandpaper, or a Scotch-Brite pad, to sand/scrub off the haze.
Or perhaps try some metal polish (with very fine abrasive) to remove it. (Edit: I see you've tried that already.) Whatever you try, just do a very small spot initially, to see if it looks like it'll work. Might even post a pic or two here of the knife, so we can get a better idea of what you're seeing.
I know I've seen a similar post from someone else here, a while back. I think I replied in that thread too, and if I can find it, there may be some more details as to what's going on. I'll link it here if I find it.
Here it is. This link goes directly to a post in an older thread, with a very detailed description and pics:
http://www.bladeforums.com/forums/s...-can-go-wrong-with-them?p=9988190#post9988190
