When you get a stealth kill with daggers it doesn't count towards building your 1h tree? How are other assassins of the night gaining this skill?

I think your stealth kills with dagger do count towards building your 1H skill. Same with sneak archery kills.

I gain this skill as I play the game, but it's been slow, so I plan to buy training.

I messing around with my first stealth toon and I am clearing out the small mine by river wood and I am leveling stealth and archery like crazy but my 1h has not moved. I hit with a bow first then sneak backstabbing or cut throat everytime.

When I start to play for real, I will pay closer attention to it. It might just be leveling a lot slower than I thought it would.

Sneak kills with dagger levels both sneak and 1h. Speaking as someone who has leveled sneak to 100 during tutorial by backstabbing on 2 different chars.

Is this even possible in a dungeon? After the first arrow there's no chance I could ever get behind the enemy, they look in my direction and the majority of the time there's no alternate route for flanking.

Because of my low skill it does make it harder and I'm going with higher stamina than health so I can just run in there and get some. It takes a little planning and a lot of shoot, run and hide, sneak attack with dagger. Takes a little more time but will be worth it at higher levels.

Depends on the dungeon. If they don't find you after you killed somebody with a bow and you wait long enough they return to what they did before.

One hit stealth kills will probably level you slowly as you don't use the weapon much

In this situation I shoot an arrow beyond the target and move forward while the distraction exists. If I can get behind them while they are walking toward the noise I pop them good ^.^

P.S. Damn I love this game!