"The downside to using daggers is that they do not have a weapon specialization (they get a perk in the Sneak skill tree instead which works only with sneak attacks) and they do not benefit from Fortify One-handed effects, which can dramatically increase the damage output of one-handed weapons."
Reading the first line will not teach you anything. If you do not believe the wiki test it for yourself...
The Armsman Perk does increase the Damage of Daggers. I've tested it many times myself. The "Fortify One-Handed" Enchantment or potion however, does not improve the damage.
As for the Topic.
A better, more emergent world that really utilizes Radiant Story in a more effective way. The Thieves Guild represents the pinnacle of what Radiant Story can do, and if applied globally across Skyrim, can really allow players to shape the world around their character in an organic way.
Just some examples:
Bounty Quests improve the economic status of the hold they're completed in, slightly increases merchant gold and stock quality at certain watermark intervals. (Cap should be relatively high and hard to reach to make it an ongoing process.) The Thieves Guild accomplishes this with the Delvin/Vex jobs.
Homes and structures repopulating with "Generic" NPCs if all occupants are cleared. We already see this happen with Forts. This would really make Markarth a more appealing city, since during a certain quest, there's a high probability of depopulating the city.
Better Radiant Rewards. Gold is a fairly worthless commodity in Skyrim because of the lack of a destruction engine to cycle it out of the system. The college actually solves this issue with "Shalidore's Insights" special scrolls. Increasing the spread of this idea would be beneficial to the incentive of questing. It needs to be consistent in the factions, particularly the Companions.
Scaling back of certain Radiant Rewards when they do not make sense for the quest. Great Example is the finale of the Civil war quests. Getting a "Generic leveled Sword" at the end of a faction line is an insult. It doesn't have to be an item necessarily, just something meaningful.
My secondary, and much more realistic desire for a Skyrim Update, is to give all appropriate enemies a decent Armor Score. A Bandit Chief shouldn't really have an AR that does more than Double his effective HP, but a Centurion Master seems like he should cap out the AR, maybe even overcap to defend against a certain degree of the Mace Perk.
Additionally, with this, Weapon Spec perks need a buff to enhance their differentiation. The idea for "Balance" Would be that the ceiling of average global DPS remain the same, but require the player to invest in these perks.