There’s an incredibly detailed WW/Rend guide on the US Barbarian forums…
It covers all the gear needed, prioritisation of affixes, weaponry choices (e.g. speedfarming, solo pushing), passives, rune choices, play-style and so on.
Immediate reactions to your seasonal Barb - Saskia
Helm. Should be STR / VIT / 6% CHC
Shoulders. Reroll the 15% Life to 15% Rend
Chest. Should be STR / VIT / 15% Rend
Gloves. Rend doesn’t benefit from Attack Speed. Reroll AS to CHD
Bracers. Should be STR / VIT / 6% CHC / 20% Physical
Amulet. Reroll the 17% Life to 10% CHC. You should consider a Squirt’s Amulet rather than the Hellfire Amulet as, when you click a shield pylon, (whose duration should be doubled by your follower having a Flavour of Time amulet emanating), this is essentially 1 minute of double damage.
Band of Might. You need a new one as Rend doesn’t benefit from Attack Speed. At least STR / CHC / CHD. Ideal is CHC / CHD and Area Damage or Average Damage.
Convention of Elements. Consider rerolling the average damage to 50% CHD, but you need a new one as this one has rolled with 150% on the legendary affix, when the range is 150-200%. You need one with 190+ on the affix, and at least STR / CHC / CHD. Ideal is CHC / CHD / and Area Damage or Average Damage.
Legs. You need new ones. STR / VIT / All Resist.
Boots. You need new ones. STR / VIT / All Resist / Armour.
Weapons. You’re missing CDR and/or Area Damage from both of these. Of course, these are BK weapons, so only really for rifts / speedfarming lower level GRs. You’ll need Istvan’s Paired Blades (Slanderer + Little Rogue) for GR pushing.
If you’re using BK mighty weapons, you should never be running out of fury. That means you should rune WW with Blood Funnel for the healing, allowing you to swap the rune on Battle Rage to Into The Fray, giving 1% extra CHC for each mob close to you.