This is not really a new idea, but I think it could be worth a revision.
As you know, the idea of HAZ-only items has been circulating around for a while, but creating interesting new items for all levels (20 to 55) might be a little difficult. I propose instead the following:
All items of Superior quality and above that are scavenged in the HAZ would have a chance to have a stat that is not originally present in the item, in a similar manner to crafting kits. However, unlike crafting kits, these would actually be able to add characteristics not obtainable with them, and possibly add new ones that no crafting kit can give, or even stats that no other items have, like those that have been suggested in the forums (such as knockback resistance, critical hit chance, etc).
This is a sample of what I mean:
Obviously, this should be balanced according to the item type, and it would focus not in the average damage/APS/range increase, but in the versatility of the item (for example, adding Trap Spotting to a weapon). Also, since we can't choose wich item gets which bonus, and since they won't have crafted bonuses, they could be a little more risky in the balancing of the amount of bonus they gain.
Boring? Too OP? Any comments or feedback will be greatly appreciated :)