The usefulness of Echoing Fury is dependant upon the number of stacks of Frenzied (that’s the buff from EF, not the stacks of Frenzy the Barb ability) you can maintain. However, those stacks are obtained / refreshed on kills, not hits. This means the higher GRs you push, the less often you’re killing stuff, which leads to it being harder to maintain stacks of Frenzied. It’s fine for speed-farming, or low level GRs, but the higher you push, the less useful it becomes.
Also, as for Guardians, if you get one without adds, EF isn’t useful at all, as you’re not killing anything to maintain the stacks. If you get a Guardian with adds, you’ll get stacks, but some of your Stricken stacks will be wasted on the adds.
Wyrdward isn’t used on the hero. You’d either have to be giving up COE (big loss of damage) or BOM (big loss in mitigation). It’s not worth it.
If you like the style of H90, but find it too squishy, in the upcoming Season 22 where seasonal heroes will have access to a 4th Cube slot, there’s some interesting discussion on the US Barbarian boards about hybridising 5 pieces of Immortal King with 2 pieces of H90, and playing HOTA. H90/Frenzy and IK/HOTA play quite similarly, but IK/HOTA has a lot more survivability due to incoming damage being shared between the hero and the Ancients. By including the 2 pieces of H90, IK/HOTA gets the benefits of doubled shouts.