First: no matter how well your attributes and skills are you can't make iron better then steel period.
I suggest to add quality to resource type not from how good your skills are, this will help both new players and veterans, new players will be able to find rare resources which will be higher quality and trade for thing they need and veterans will spent less time looking for better quality resources and spend more time doing other things, both win.
To work with better quality resources you'll need a higher level skills, this is where your skills and attributes play a role.
Scavenging will still work as it dose now, better scavenging skills will have better chance to find rare resources and more often.
This will simplify coding for Xsyon and help economy in game.