At least on the UESP, they are on the one-handed (1H) weapon skill page, and clearly they are 1H weapons (duh), but I read somewhere (sorry, don't recall where) that they do not benefit from 1H perks and skill bonuses. Other than my allusion to reading it somewhere, you 'll notice that swords, maces, and axes all have skill-tree branches under 1H weapons, but daggers do not.

Any info here?

Thanks.

AFAIK they benefit from 1H perks (although they don't have any of there own in the 1H tree), but not from the "fortify one-handed" effect from enchantments or potions.

Info from UESP:

"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. Temporary enchantments like the Elemental Fury shout, poisons, weapon enchantments and the Armsman perk do work with daggers."

Daggers are really viable weapons. They swing really fast and uses very little stamina for power attacks. If you have damage enchants, like fire or shock, you can deliver that extra damage a lot more often than if you were using any other weapon. If you do not use fortify one-handed enchantments or potions, dagger is arguably the best weapon even for straight up, no sneak fights.

I'm going to take my advice and try them out myself. It's strange that I haven't.

Some comparisons:

Early game:
Steel Dagger (5 damage, 6.5 dps) is a lot weaker than steel sword (10 damage, 10 dps)
With regular legendary smithing it's still slightly worse than steel sword. (19.5 dps vs 20 dps)
If you add damage enchants, let's say 10 fire damage, steel dagger has better dps than steel sword. (32.5 dps vs 30 dps)

Late game:
Daedric Dagger (11 damage, 14.3 dps) is already better than Daedric Sword (14 damage, 14 dps)
With smithing and enchanting, if you add +20 damage, the dagger has significantly higher dps than sword (40.3 dps vs 34 dps)
The advantage carries over with skill enhancements (1.5x at 100 skill), and base armsman perk (2x) (120 dps vs. 102 dps)
If you add 20 fire and 20 shock damage to that you get 172 dps vs 142 dps.

Daggers have their own perks in the Sneak perk tree.