Check http://360junkies.com/xbox-360-system/1542-brinks-digital-pre-order-bonuses-can-i-haz-them-all.html out. It DOES say the Green-eye scope is exclusive, but the suppressors that come with the Psycho kit are described as "new" unlike anything else we know to be exclusive. What do you suppose that means?
Well it clearly says "The Resistance’s
improved Soda Can Silencer..." Either there's a Soda Can Silencer in the game normally but this is an improved version, or it's saying the Soda Can version is an improved version of the regular silencer. Which makes sense because you can't say a scope is "Improved" because the scopes are all gonna be personal choice things. Do you want the red dot, do you want a scope, do you want the iron sights, all of those things are dependent on personal choice. When you look at the silencer, and the second one has undeniably better stats, then it's improved. And seeing as the Silencer is the only part of the Pre-Order packs that could be labeled with "Improved" then it makes sense that it's the only one that is.
I have noticed the "Unique" on the tattoos, and my only conclusion for that is... They're called that because when you choose your tattoo, you have to stick with it. The clothes you can change, but the tattoos you can't so they're "Unique". I dunno though.
Or they could just be referencing to the artwork, saying they're much different than anything you can find in the game.