does defense behave like " block" or "armor penetration " with a 1000 points maximum or is it limitless some sort of exponential thing ? Like at 200 defense you get 30% added parry chance, but with 400 defense you get just 45% parry chance and so on until the unreachable 100% parry chance ? Im quite sure its the last one

Or its just a stat/speciality thing. Buckler for Agi builds, Wallshield for tanking slow meatmountains (Like cant move...sooo i just put that huge obstacle in his way) xD and kite shields for some crazy hybrid builds?
Some sort of Agi for "activ" and Str for "passiv" parrying.

Thats why bucklers are good or should be better against onehanded weapons... they cant dance arround you so easly because you are as fast as they are. The same for big shields vs weapons.

Im excluding all skills because i want a basic rule not specific situations with those defense ignoring skills