"Powerful" is not a good word in this context. Two-handed weapons and their animation look more powerful, but I think that dual-wielding two one-handed weapons results in more DPS (Damage Per Second). If it is for the looks then choose two-handed weapons. If you want DPS then it is likely dual-wielding of two enchanted weapons with double enchantments and a high attack speed.
I cannot be bothered with blocking. If something attacks me do I kill it with speed just so I can continue exploring Skyrim.
I cannot be bothered with blocking. If something attacks me do I kill it with speed just so I can continue exploring Skyrim.
I don't dispute that dual-wielding can result in higher DPS than 2-handers (not that I've done the research myself), but the "feel" of dual-wielding to me is pretty repetitive. Not the look, mind you - the feel. For best results, dual-wielding seems to depend upon dual power attacks, which requires you to stand in place. 2-handers need PAs too, but can achieve them in different circumstances (e.g., moving forward), giving more mobility.
The fact that you can block with a 2-hander also opens up Quick Reflexes, which really lets you feel like an agile swordsman - when the enemy winds up & time slows down, you can dodge around behind him and hit hard with a PA of your own.
So yeah, you can grind out more hp from your enemy with dual-wielding, but there seems to be a better rhythm to combat with 2-handers in my experience.
Also in my experience, I haven't noticed an appreciable difference in speed between attacking one at a time while dual wielding and swinging a single 1-handed sword. I haven't explored dual-wielding a lot, though, so I could be missing this aspect.

. I use '28% alchemy gear' to create smithing and enchanting potions, then use the potions together with '28% smithing gear' to improve the weapons and to enchant them, and then I wear a ring, a necklace and gloves enchanted with fortify one-handed in fights.

