I see this as a lot of work, that is not very difficult. Maybe a tutorial is in order? The question is too generalised for a quick post to answer.
I'm not sure that I'm the right person to do it, because I know many people here do a lot of skinning and custom armour and weapon making, and will know all the pitfalls. Personally, I've not done much in that way. I have switched out monsters, and re-textured towns, mobs and armour, but not actually done much with Armour stats and such.
I have an understanding, and will undertake a tutorial / guide if nobody else is willing or able.
Celestialzero asked much the same in
their thread a couple of days ago. Some of what we discussed there may be of help, but it's pretty terse.