First and foremost, thanks for the guide. I'm having a blast right now with this character, most fun I've had with MXL.
Playing around I have tweaked the build a bit, I noticed a severe lack of AR which diminished sustain and also, IAS for WW, bringing it from 10 Frames down to 6, helped sustain from LOMA and added more proc chances. Also, use Oil of Conjurations on weapons, success will add +10% psn dmg or if you struggle with AR, use Oil of Greater Luck.
I went with Crown of the Black Rose for a Helm, massive psn dmg and pierce. Though, if you are farming fautz/bremm/dunc, Amanita might be better than for the Time Wave proc. Keep in mind, you can buy a time wave relic for relatively cheap, I think I got mine for around 35tg.
For Gloves, I'm not a fan of Memory or Mith. I use an Abandon craft gauntlets with ~100% AR, ~20% psn dmg, Flat stats + % to dex (help with AR more). Also, try for Burning Veil Proc on kill, it will increase your damage quite a bit. It brings me from 500k to 550k. (You do not need IAS on gloves, WW is only affected by IAS on weapons)
Everything is about the same. Sadly, there arent enough pieces with flat psn damage to create a larger build diversity. Would be AWESOME to see a relic with +psn dmg over time, this would free up all gear slots to possibly take this build farther.
I keep an entire separate set of MF gear for Fauzt since it's 100x easier to clear than Scos. The MF gear is ~480% MF with 400% psn dmg and ~150 pierce.
Here is a link to my Notarmory if you want to see anything specific. https://tsw.vn.cz/char/ChewableTrash
Here, I put 2 IAS runes to go from 10 FPA down to 6 FPA... This has made a MASSIVE QoL improvement with sustain, especially in Scos. Also, procs, who doesn't love em?! Sadly, Oil of Conjuration didn't work.
These gloves aren't the "best" stats but it provides a massive increase to AR, massive psn damage, some pierce, a proc (Burning Veil) which also increases dmg. I use these as I continue to roll Abandon Shrines on another pair. Ideally look for the Burning Veil proc, AR, PSN dmg/pierce, % dex for AR, and some other relevant rolls like Vita or LOMA/MF. This took me A LOT of shrines because I ONLY kept good rolls if Oil of Luck worked for the Physical Resist +1%, otherwise keep rolling!!!
Here is my overall Barbarian right now, keep in mind my build is aimed more-so for farming Scos. My MF build is aimed for Fauzt. MF gear is in inventory.
Hope this helps a bit. I'm still fairly a noob myself, so I know I might be missing something or have over looked other aspects. Always open to constructive criticism to better myself! I'm sure there is more room for improvement.