Great Hunt seems to whiff completely under certain conditions. Most noticeably if an enemy is standing still and you hold/spam click to attack them every 2nd hit will whiff if you're under fury. I am playing 1.3 but I've also noticed it happening in videos from about a year ago, here are some examples:
https://youtu.be/bZD10NHdW8g?t=1536 25:36 to 25:44 show a couple instances
https://youtu.be/PHGxA2UhiKQ?t=490 Very good example from 8:10 to 8:18, note how at about 8:15 the fury runs out and the now-downgraded Great Hunt hits every single time.
These are from an older version but, again, completely consistent with what I've experienced ingame. I've also tested with a low-damage weapon on /players 8 destruction zombies/skeletons in blood moor, 0% total character speed with a very slow pike or 20% total character speed and +130% IAS buff from takedown make no difference in the behavior, specifically every second hit is ignored.
I say "under certain conditions" because it seems like that's not the only strange behavior it's exhibited, but the most consistent, game-affecting, and easiest to replicate. Over the course of my spearzon play I've also gained the impression that great hunt does very poor damage against targets standing right by a wall, and specifically against the K3KBA totems if there's a bunch of skeletons in very close proximity but I can't yet say anything for sure in those cases.
Edit/Update: I'm noticing the exact same bug with Pounce as well. At first I thought the skill just had a targeting quirk (if you hold click or click too fast it'll pounce the same spot twice before moving on the next pounce) but it actually does no damage on the second pounce as well. After some short testing it seems that while under Fury every second attack of Takedown, Pounce, and even the normal attack, not just Great Hunt, do no damage to the target. Also Pounce which moves freely if you hold click while not under rage will start pouncing in place every second attack (the one that does no damage).
So basically something about Fury seems to break the entire Spearzon class skillset. It's hard to tell if Hyena strike is affected or not because of the constant poison damage. I suspect that it is though because I've had puddles/health gloves appear from it that didn't seem to do anything, which I bet this is to blame for.