Simply altering equipment in module_troops will often work good enough with a few caveats which you may run into and will have to try and fix them.
To add new items, you just add all the items into module_items.py, look at other items for examples. If your item is similar in function to some other item you can just copy/paste that other item's entry and change item ID, name and model name, along with tweeking other properties if needed. Item ID is for calling in code ("itm_new_armor"), name is the item name you see ingame, and model name is reference to model name as you named it in openBRF.
Order of the item on the list (in module_items.py) can sometimes matter, you can get unexpected bugs during game run, NW performs some checks where order of items count, I don't know them all by heart but it is best you just keep items of similar class grouped together (so for example put new pistol with old pistols), ideally add new items somewhere in the middle rather than below existing items of same class.
If you added your items to module_items and equipped both players and bots with them in module_troops, and you still see naked people running around, check if you did rigging part properly (is your armor actually attached to the test model in 3e view of openBRF) and if not read up on some basic tutorials about adding items in NW or WB module systems.
