When I stack up all of my +one handed damage equipment and compare before and after with daggers there is no change

If I do that with swords they go up by a ton

So if item +1 handed dmg doesn't apply to daggers , then do the perks either? Are my 5 points in 1 handed dmg boost wasted?

Nope. They're counted as stealth weapon apparently. Weird. They should fix that on the next patch.

Daggers have a few issues.

I can't upgrade steel ones, and they have problems in the quick item menu.

I don't know what the story is, but it seems they get treated somewhat differently to other weapons/blades...whether that is by fault or design I can't say.

Edit:

Well, if they are counted as stealth weapons, then something needs to be done to fix the dual-wielding and quick menu issues...because putting a sword in one hand and an axe in the other, then doing something else like casting a spell from the axe-hand screws things up...because as soon as you reselect the axe hotkey, it goes straight to your primary hand (works like that for every one-handed weapon except daggers, I think).

By that logic they should get higher damage in sneak gear... hmm I have not looked at that

One of the perks with knives does 15x the damage.

They do, my current character uses a glass dagger(superior) with 15x dmg in sneak.

Odd. My skills increases when I use them, and the duel-wield perk affected them.

they do to some degree, I know the first stealth bonus perk 6x dmg with 1handers does apply to daggers, and I think the chance to get crits with 1handers applies to it too, but I can't confirm this as I can't recall seeing it during my play session today.

The 1-hand perk does effect daggers, just one-hand damage bonus effects beyond that don't (I've tested this personally). Even if it didn't, though, if you get the daggers perk in the stealth tree you can one shot basically anything with a melee sneak attack. I think the idea is that you could play a pure thief and not have to put perk points into 1-handed (even though your skill will go up).

With a certain perk and a certain piece of gloves, daggers do x30 sneak damage.

I have a pair of gloves that adds double damage to sneak attacks with one handed weapons. These affect my dagger causing me to do 30x damage while sneaking, so they must share some attributes with one handed weapons. Although we probably won't be certain 'till the Creation Kit is released.

I'm a sneak/archer with 0 perks in 1hand. Bonus 1hand dmg items dont work, not sure about the 1hand perk dmg bonuses.

Not really true about 1 hit killing with 15x sneak dmg perk, but you can get 2 or so dagger strikes in before being detected. I havnt had any trouble, yet, running around with 0 1hand perks because a glass dagger (legendary)'s base dmg is 24 x15 = 360. Two 360 strikes before being detected can take out most things.

Theres two ways to become practically invincible with the sneak/archer/thief build.... add paralysis to a dagger or abuse the 100 sneak perk where you can instantly hide in the middle of a fight. With the latter, no matter how close they are or what they are doing, you will be hidden for a brief second... which is enough time to get a hit in with the dagger (meaning a 360dmg hit at any point in the fight).