You can win with on-hit but I don't think it's optimal. Bruiser works better vs tanky teams. If you go for mostly attack speed items, it's hard to get enough attacks off to make them worth it 'cause you'll be quite squishy.

Duskblade of Draktharr gives you ability haste, which lets you cast your ultimate more often, and invisibility after you 1-shot someone. It also deals basically the same damage as Eclipse until later in the game, when Eclipse's mythic passive is stacked up. I'd recommend Duskblade as it'll give you more opportunities to get kills and you'll be safe from being focused after killing someone, because you'll be invisible long enough to reposition.

Generally when the enemy team isn't squishy / vulnerable enough to use a full damage build. If you're against a lot of tanks/bruisers, peeling supports like Lulu, and the enemy team is going to be grouped a lot of the time, it can be basically impossible to reliably 1-shot someone.

The Bruiser build still lets you kill people, but you'll do it over time and you'll be a lot tankier for team fights. It's not as strong at carrying, since getting picks solo is more difficult (the enemy has more time to escape or get help), but it guarantees you won't be useless in team fights.

For example, I used the bruiser build against a team with Renekton, Rek'Sai, Sylas, Miss Fortune and Maokai. I could probably kill any of those champions with the Assassin build if they were alone, but when grouped, my only viable target would be MF (and she built Zhonya's Hourglass that game). Instead, I was able to fight anyone on their team, even in team fights, since I couldn't be bursted through Sterak's Gage and had enough DPS from Lethal Tempo to kill their tankier guys.

Wow, I didn't even realize they changed the name. Thanks for the tip, I'll update the guide now.

Lethality items look pretty good but it's hard to say for certain what options there'll be. Nocturne has historically had pretty radically different builds based on which items are strong. I'm hoping we'll end up with more build flexibility than there was for Noc this past season, but there's a lot of uncertainty with PBE testing so I'll reserve judgment for when the preseason patch actually goes live.

I usually post a comment for any major updates.

I realize a lot of people play Nocturne differently with different builds. I've seen all sorts of stuff like Cinderhulk + Titanic, Bloodrazor + Cleaver and the crit build you mentioned. Basically I only want to include suggestions in my guide that I have enough experience with and feel comfortable recommending to other players. That doesn't mean that there are no other viable builds, just that I'm not going to recommend them to my readers.

I spent some time with the crit build and it does feel pretty powerful (I'd say roughly on par with lethality with better DPS against tankier targets), but I found it pretty lacking in CDR and flexibility. If you're going crit you really need 2 items to get going (PD/Shiv and IE) which doesn't leave you much room for defense or CDR. It feels good when ahead and not great from behind, which to me didn't seem to provide much benefit over my usual playstyle, so I stuck with lethality.

As for Bloodrazor builds, they just seem really weak at actually killing carries which is too important for the way I play Nocturne. I used Devourer + BotRK a long time ago but I'm not happy with the Bloodrazor power spike, whether it's with BotRK or Cleaver or both. It always takes several seconds longer to kill carries which just leaves me feeling pretty vulnerable. You definitely have to play this kind of build quite differently and I don't have much success with it, so it's hard for me to recommend to others.

As for Death's Dance, it seemed pretty promising after the buff but I already have a ton of CDR sources in my build so it's usually overkill in that department. It overlaps a lot with Ravenous Hydra and I felt Hydra did the job better. The only advantage DD has over Hydra is the bleed, which in my experience wasn't terribly helpful on Nocturne compared to other champions. I didn't find myself in situations where I could sustain through lethal damage or escape with 1 HP. I could see it being better with a crit build which has higher DPS, especially since it helps offset the low CDR from that build.

tl;dr: I recommend lethality and mixed defense items because I have the most success with them and feel comfortable recommending them to others. Lots of people make other builds work all the way up to Challenger so I don't claim to have the only viable playstyle.

I hope that answers your questions, thanks for the comment.