Unless some OGs pop into this thread, your best chance of finding help is here, friend:

http://tamrielfoundry.com/forum/classes/nightblade-class/

My main is a khajiit stamblade...totally my favorite. I agree with Raven's post and I like those bars. I'd add a few add'l pointers.

- with One Tamriel, levels 40-49 have become the most difficult segment of character progression. The game "handicaps" you at a low level then slowly removes that assistance. People often have trouble at these levels...don't worry, you'll get to vet some day then start earning champion points and it'll feel like a whole new character.

- that said, One Tamriel's math also destroys you if you outlevel your armor. Do not let your gear get more than five levels under you or it will become worthless.

- vigor will change your nightblade's life. Seriously. I know you don't want to pvp, but my nightblades rely on this burst heal...11k over five seconds. You need 85,000 AP to unlock vigor...pop into a campaign now and then, help defend a keep or two, help take resources, and repair keep walls. You can get to assault 5 in a couple of pvp sessions. And if you're willing to go a little further (15k more AP), caltrops is a MONSTER aoe for a stamblade.

- Hundings and night silence is a great combo. There aren't really better sets up the trait scale...honestly you can wear this setup all the way to c160, and even beyond. For many, many moons I wore these plus a monster set, or agility.

- for down the road, I absolutely love Briar Hearts on my tamblade, paired with Hundings. A crit strike has a 10% chance to proc briars, which increase weapon damage by 500 and make each crit hit return 700 health. If you have a good AOE, you'll do soooooo many crit hits and get so much health back it's ridiculous. You can't farm it now because you don't want low level gear, but you can watch for good deals in the guild stores. The jewelry is what's hard to find...you really want c160 purple robust jewelry. It's normally 100k per piece if you can find it, but I just found a necklace for my friend for 1,800 gold, so watch for it.

- you're at a good level to start using the right armor setup in addition to the sets. Wear 1-2 heavy and the rest medium. Chest, legs, feet, helm get you the most bang for your heavy piece(s), pick from these. Invest in all medium passives and the first three in heavy. You should start wearing blue armor, if not purple. You should definitely be using purple weapons, sharpened or precise traits. Enchant your gear, green or blue glyphs. Mostly stamina enchants, but if you're squishy make some health...just until you grow out of this awkward level phase. Armor traits can be divines or infused...but if you still have a load of skills to level you can still wear some training pieces.

- you're also at a good level to start using the right jewelry enchantments for your character. Eventually, stamblades transition to all weapon damage enchants. On three pieces c160 with gold enchants...that's 475 add'l weapon damage. For right now, try a blend of green or blue weapon damage and stamina recovery enchants. That should help. But experiment with giving up the recovery...a stamblade should invest in power. If you need stamina in longer fights, learn to use siphoning attacks and thread in light and heavy hits.

- you're about to unlock Undaunted. When you do, run dailies if you like...but definitely start doing the Undaunted delve daily. It's given out at the undaunted enclaves by an Orc...Balgara or something like that. Undaunted takes a long time to level, but there are some decent skills in the line. Doing the delve daily is a good way to get that process started so it doesn't take you years to level.

- sadly, bow is reeeeealy hard as an attack bar in pve. I have a lot of success with it as a back bar, or if running with at least one friend I can make it an attack bar. Solo, though, the bosses get through and wail on you.

-the dual wield bar is made for stamblades. Your damage will be higher, and so many of the skills stack sustains. They're all good, honestly, but of note:

1. Bloodthirst is lethal, and its heal is significant. On a stamblade I find the heal to be as good/fast as funnel health, with a ton of dps tossed in to boot. Used well, the dps on this can rival poison injection.

2. Blood craze offers a substantial heal too. Stacking craze and thirst can provide a LOT of health back.

3. Shrouded daggers: I was sad when I eventually had to give up my bow attack bar. I love ranged play. This ability gave it back to me...in pve it's a powerhouse. The dagger bounces to three targets AND you get major brutality for 20 seconds. Our dps will be way different because of the levels, but to give you an idea my snipe crits for about 25k. Poison inject's initial hit is like 5k. My shrouded daggers crit at 11k the first hit, 12.5k on the second, and 14k on the third. And it's dirt cheap. Putting out over 36k damage per cast is way powerful.

4. Rend: the dual ultimate is a juggernaught for stamblades, especially in the battles you're saying you have trouble in. Work that dual line to 50 then start using this. On my stamblade, it does like 45k damage over 16 seconds and heals me for 50%. Massive dps and heals right when I'm in the fight of my life? Yes, please!

- in 2h, rally is an excellent skill. It provides major brutality and a small, consistent heal for 35 seconds. If you use shrouded daggers for major brutality and one of the dual healing abilities, you don't need this. But it's a great ability otherwise. You're at a level where you need to make sure you're buffed with major brutality during all big fights...20% more damage is essential for you.

Good luck! Feel free to message me any time with stamblade questions. I feel your pain...they are hard to master, and squishy and frustrating until you find the setup that works for you. But when you do get them all set up the way you want, they are a whirlwind of blood and death.