Something like this would require unique models and textures, for each individual part of each individual weapon. Each blade, cross guard, hilt, wrapping. Integration in the lists is easy, you just add the items to the list essentially. The hard part is actually taking the time to make each model, texture it, then do the same with any variation of finished product. Then you have to make sure each possible weapon variant will work properly in the world, with animation and movement. You also have to overhaul the crafting system, removing the current one and integrating the new items, then working out cost of product and ensuring that won't be an issue with Skyrim's current economy or the existing amounts of resources in game. It's a massive undertaking, and probably part of why F4 took so many years to make. But I like it and want it.