The data for the weapons are usually in the preorder.bin file and one of the other bin files. You need to use Kane's bin upacker and repacker to mess with the stuff. But it'll be a lot of guess work for you to edit, since not much is known about the insides yet. We only have a few basic understandings about it and such for now.
dlc weapons are in the \deadrising3\dlc\ folder. There is 1 .bin file for each episode that holds all the items for that specific dlc. Also Solid, I do know quite a lot of information on items in DR3 and alot of it is posted in the Tutorials/Resources section. Hope this helps!
Mhm I know Tommah but I said "we" as the people who are just starting out in it or attempting to mess with it. You and I believe another user are the only ones who have dived further in and got a good understanding of it thus far.