Ethereal

Dont forget this is not only a game. Its a role-play game. If I feel my character is a two-handed weapon warrior, I probably wouldnt have wanted to have a shield.

For game-mechanic. Shield still takes up an enchanted item slot, so you could just wear two pieces of armour instead. The only thing you lose is actually the block skill. :)

Most of the defensive enchantments you would put on armor, you could put on shield.  Defensives on shield, offensives on armor, win win.  So there is really no loss to equipping a shield, it seems.  Just bonuses.

Not necessarily-

You lose the ability to have evasion and make for an easier target than someone who has evasion. But as a trade off for not dodging attacks you're able to sustain more damage per hit. Using a shield also keeps you from equipping artisan trinkets and stuff if you already have a weapon and armor on too-

So then you're driven to choose between having max damage on your weapon or sacrificing a slot or two toward being accurate with your strikes. T-T