That's the way it works IRL. A shield is designed for defense with maximum coverage , a two handed weapon is designed for offense, more concerned with doing heavy damage due to it's mass. A 2h weapon is so much slower because of it's mass, it will be less efficient as a blocking device, A dagger is commonly used quite effectively in a dual wielding situation with a sword in the primary hand and the dagger in the off hand (typically a large dagger called a Main-Gauche which is French for "left-hand") used to parry incoming blows, because of its speed and maneuverability, it's quite effective in that role. Speed and maneuverability trumps size and mass when it comes to effectively blocking and parrying attacks.
Actually, size, mass, and
reach do trump speed and maneuverability. You don't have to move something into position when it's there in the first place. "Parrying Daggers" are only effective against lightweight weapons, and came about as the Rapier became a dominant Civilian weapon. And even then, it takes incredible skill to get it to work effectively.
A Main-Gauche is used as a dueling weapon, paired with the Rapier or Smallsword for combat against single, unarmored enemies using a similar setup. Greatswords don't get much civilian usage because they're unwieldy in social situations, expensive, and overkill against unarmored foes.
Of course, I guess the thing that IS effective with Greatswords in Skyrim is the bashing ability - Especially once you get Disarming bash.
have you ever held a Greatsword?! moving that thing around is most definatly not fast, if you know what your doing im guessing a dagger wielding agile warrior would put you down in seconds same with a light and nimble sword. not to mention daggers can change direction mid-swing a greatsword cannot without alot of effort and leaving all sorts of openings for those killing blows.
It is fast if you don't
swing it around - You simply maneuver it around its center of mass. You don't need to do this with a dagger... but you can't get close with a dagger against a Greatsword because the Sword is already and always in the way.