EDIT: Warning, long comment ahead!
TL:DR:
Fury stronger cuz better items this season.
For Pure ST use: Deathmaker Leg (cloak), NF Dreamweaver and Dragon’s Roar Talent.
For mixed ST/AOE raid fights (like Anduin) use: Signet (ring), Bastion Mike and Bladestorm. Make sure you have Bonegrinder conduit activated aswell!
(Your ST is not high enough to go full ST build, but AOE burst window can pick up the slack)
That is because the current season caters for Fury.
Fury uses Gavel + Jaithys.
While Arms can only use Gavel.
Trinkets are the same for both specs.
But haste caters a little more to Fury, so OWS on fury is slightly stronger.
The set pieces also cater more towards Mastery, which again is Fury favorite.
That is because ppl don’t bother with creating 2 legendaries.
Also getting signet to proc Reckless+Avatar is nice.
If it procs Bladestorm you just insta cancel it and act like nothing happned (also lost use off your Legendary)
I actually used to use Deathmaker on cloak for Fury and it does ALOT more dps.
But ppl also use Necrolord alot for ST Fury because it “Sims” higher. But it barely ever outperforms Dreamweaver for ST damage.
So I’d say the “issue’s” you have are simply a “wrong” (not rlly) choice off build.
Wowhead also says for ST damage (Raids):
Necro > Kyrian/NF.
Which means, Kyrian for AOE fights, NF for ST fights.
Don’t use Necro unless you want to gimp yourself.
Also.
Scars trinket + OWS are absolutely broken for raids and ST damage. I use both permanently because you never lack AOE damage, but need some ST damage in M+.