I think I'll go for the light shield as a tactical option on my current dual-wielding light armor warrior.
My idea is that I could spend only 5 perks in the block tree to get the greatest value out of my shield for the lowest cost: Shield Wall (1/5) > Deflect Arrows > Elemental Protection > Block Runner > Shield Charge. The first point in Shield Wall yields the most (+20% compared to only +5% each point after that) and all the other perks are potentially very useful, especially combined with Block Runner. I could then have the option of whipping up the shield while running into melee with ranged attackers and greatly reducing the damage I take. Once in range, bash, then go d/w for the kill.
Also note that the damage reduction of a shield's block is not based on its armor value at all. It's all in the block skill, modifiers (perks, enchants, potions), and of course correct timing. So for blocking, a simple hide shield is as good as a legendary daedric shield (though the armor value is different, but that's a separate mechanic).
Going dual-wield + situational block can seem a bit too costly in terms of perks. I would point out though, that the light armor tree is less perk-intensive than hvy armor, and perking into d/w only eventually costs 3 extra points. This warrior is my third proper character and by now I'm way too lazy to spend a lot of time or perks on crafts (try ignoring alchemy entirely and see how much more fun you have!), and he's no mage or sneak-thief, so he's got the perks to spare.