Thanks for your feedbacks and advices (actually I didn't expect any, given the high quality of what have been posted in the previous pages).
I've read about Substance Painter, it made me feel like an oldman discovering new technologies.
Now I want to stop with Wings3D and restart from scratch with Blender, PS, Sculptris, xNormal, Substance Painter, Unreal Engine for rendering etc.!
It is probably essential if one wants to make decent models for Bannerlord, whose graphical quality, even if not amazing, will be much better than Warband.
Btw, do you think sculpting can be useful for modelling simple architectural structures?