What made people play Mount and Blade series at the first place was, it offered a basic combat system that's easy to learn hard to master with no fancy features/perks allowing for a smooth uncomplicated gameplay. I don't think implementing some kind of stamina feature for combat will do any good to be honest.
Now i don't know what we're getting with the Bannerlord in terms of perks, but i wouldn't complain if we get some kind stamina only for running/sprinting but not for combat itself.