You need to edit the itemset.sdata in your client. If you open the file in Hex format, you'll see the information it holds, to be able to make up a true working file yourself. But editing it wont work with ShStudio, as it does not handle the file in it's current format. Either make yourself a python script to go with Zero's release, or edit in Hex to define the data you want.
And it works as a simple set bonus, to add stats to the player using.
For example, you get a low bonus for 2 armor pieces equipped, a middle bonus for 4, and a full bonus for 5, something along those lines.