When starting up with a martial arts sin, I’d recommend you clear normal how ever you’d like, but take the time to find a 4+ socket long/crystal sword for Nightmare. Long Sword is the fastest 4x socket sword available in Normal, and Crystal Swords found in the Nightmare Far Oasis and onwards will get 6 sockets from Larzuk. You’ll then want to respec to either Phoenix Strike or Tiger Tail and put 4x Eth runes in to the sword for “-100% Target’s Defense”.
This will put all normal, champion, and unique monsters at 0 Defense, and will put Super Unique and Bosses at -50% Defense. It’s extremely hard to hit with charge up skills when you have bad gear or if a monster is a higher level than you, but this fixes that issue. Works great for the blade sin as well if you choose to start with that.
Other way to fix chance to hit
There’s a key item you can find once you’re fighting in monster level 20+ areas and shop for once you hit level 30. You can find magic Katars with Ignores Target Defence vs lvl 20+ monsters and you can buy ITD magic claws from Anya in normal once you hit 30. This helps immensely when playing through nightmare and hell and since your weapon dmg doesn’t matter with most martial arts skills, they can be used all the way through the game. It’s extremely hard to get a good chance to hit with bad gear and when monsters are a higher level than you it becomes near impossible to hit sometimes, but ITD fixes that and you can save CoS for champions and such.Also when using kicking skills, there is the safety greaves/war/myrmidon boots recipe. They can be a good substitute while waiting for a solid unique or set item. Also don’t forget you can up normal level set and unique boots to exceptional. Once you hit hell, you might want to grind countess for a bit and get an act 5 merc with law bringer (Lem) or if you can trade for it, get an act 2 reapers toll merc. It won’t fix fire immunes, but it will take care of most physical immunes, and it’s also a solid bump to your kick dmg.
This is what I am for when starting nightmare with a martial arts sin:
https://maxroll.gg/d2/d2planner/e50106xv#1
Death’s sash can be farmed off normal’s cow king once he’s unlocked, something like ~1:75 chance to drop the sash I think. So definitely a targetable drop if you want to put the time in.