Define "good". Able to take on a decent 30K+ health stam DK, stamden or stamcro and kill them 1v1? Not a chance. I duelled my friend the other day on his new stam DK and I couldn't even outheal his DOTs properly and stay in the fight. Then again my philosophy is that nighblade draws fights by cloaking away. That's part and parcel of being a cloaking nightblade. You can't be tanky and have Cloak. Or can you?
The UESP build editor is acting up as I write this, turning gear to white quality when you edit something. This is my previous build:
https://en.uesp.net/wiki/Special:EsoBuildData?id=269881
I currently use Juggernaut instead of Blessed and have changed some other things around. I am back on Hissmir Fisheye Rye. I have 64 points into Magicka again. I removed Elemental Weapon for Inner Light (for the time being). It's quicker to just light attack rather than going for the Elemental Weapon into Soul Harvest into Fear combo. People move around too much and casting Ele Weapon at the beginning of the combo was often too slow. If you really want more burst you can simply open with a heavy attack.
This is definitely a good build for me, but it is also one of my oldest PvP characters and I am simply very attached to this playstyle. Building in this way allows for perma-cloaking and very fast movement in cloak. It requires you building for a lot of cost reduction. I'm only happy when I have that. I'm also only truly happy with good stam sustain on magicka characters. It's simply more fun to play, however this means I compromise my damage a lot. I don't care, though I couldn't live without Caluurion for this particular build.
The reality is that many people, those who build high-health stamdens for example, build for limited damage. They IMO build to either kill (groups of) potatoes or to gang up on the better players. It's the same with me. This doesn't mean you zerg people down, though I am not principally opposed to that, it simply means that, in a lot of cases, the better players only die when they are momentarily caught out of position and hit / ulted by two opponents or when they are deliberately focused by multiple players, who are possibly on Discord. It's the same principle with a nightblade in open world. You outright gank / kill potatoes or you help or get help killing a better player who is momentarily too isolated for his mates to help him.
Do not expect to face off squarely against better players of any class outside of cloak. On average they will annihilate you, though Juggernaut is a useful safety net. I don't aim to proc it deliberately - the cooldown is IMO too long for that - but when it does you can go on counterattack or it helps you escape. That set is the set that Phoenix wanted to be.
As far as the build, you can absolutely change Inner Light or Impale to Merciless Resolve or Dampen to Shadow Image. Regarding the latter, I find that the very high speed of my build works against staying in range of Shadow Image. The skill never really suited me.
I wouldn't really get rid of Fear. It makes people drop block and ensures a Caluurion hit.
The back bar is set in stone for me. Concealed for the speed. RAT and Siphoning Attacks, because I keep them up in cloak. Barrier for the added magicka / cloak sustain.
You might have seen my build before. If you're looking for really impressive damage, I unfortunately can't help you. A friend recommended a Stygian back bar, but I hate walking on eggshells from being too squishy or having too little sustain, including stamina sustain. This is also why I simply wear stat monster pieces to supplement the all-important stamina pool.
There will always be a cutoff point where there are people you can't kill. I have simply accepted that. Put (my) magblade in a duel and you will find that point is lower than for most other builds, but for open world scenarios it's fine. I don't think you should necessarily judge this class by duelling performance, certainly not this build.
Armour Master resto backbarred, perfected vateshran inferno front. Icy Conjurer body. Malubeth monster. Gives you great heals and resist and u procc both inferno and icy Conjurer with elemental drain which cost nothing. You are welcome
That is the real problem, isn't it. Where's the fun in not engaging someone or breaking it off after a few seconds, because experience tells you that you won't make much of a dent and you're going to get yourself killed. This is especially annoying when there are only a few people around and it took you a while to scout for a fight. On the other hand nightblade lets you get away from those tryhards that don't recognise a stalemate and pursue you forever.It just chaps my ass when I see another solo player running around there's a good chance I wont be able to have a good fight let alone be able to kill them.