Yes, because pushes with WW/Rend use Istvan’s Paired Blades (The Slanderer and Little Rogue) for the 30% bonuses to attack speed, armour and damage not because the Bul-Kathos weapon set is bugged.
A quick look at your Barb…
…also shows you’re using Skull Grasp (which only boosts WW damage, and over 95% of your damage comes from Rend, not WW, so it’s useless) and two pieces of Captain Crimson, necessitating the use of the Ring of Royal Grandeur. This means you’re missing the Band of Might and Convention of Elements. Wearing Captain Crimson also means you had to put Lamentation into the Cube, so you’re missing out on Mantle of Channelling which is another 25% damage and mitigation.
Example…