I Have a Legendary elven dagger that has 47 dmg and even with a 100 something dmg health potion while wearing 45% one hand enchanted gear I still can't get it.
Thanks for your time
Enchantments fortifying one handed don't work on daggers, only enchantment that work are the ones in the Dark brotherhood globes. The most important for Throat slit are the 2 perks in Sneak for x6 times damage and x15 damage from stealth attacks. Other than that, maybe going to the dark side with the restoration glitch to make a truly Godsbane dagger that do 10.000+ damage or more :].
Use the dark brotherhood gloves for double back stab damage. This will give you 30 times sneak bonus; if this doesn't work I'd suggest a dagger upgrade.
Not to my experience. A fortify one-handed enchantment does indeed up the damage on a dagger just the same as it does for any one-handed weapons. However, to get the slit-throat death cam, I'm not sure of the 15x stealth damage with daggers perk is required or not. Besides, I find that death cam blows your cover more often than not anyway
You should not get an kill cam if its enemies nearby. Yes this is a bit buggy but mostly with archery.
I once sneak killed an sleeping dragon with an dagger
Same. I've done that to the dragon at the word wall adjacent to Arcwind Point