These two abilities. Without a doubt the most heavily discussed warrior abilities since their pruning in WoD. I'm glad to see them back but neither ability is really selling it right now.
Overpower
1. Probably doesn't belong in the fury toolkit. It's never been a fury spell, even if the current overpower is more similar to sudden death (we'll get to that in a minute) Fury's new rotation doesn't really play well with additional rotational abilities right now, which is probably fine to be honest with a few small tweaks. But Overpower doesn't feel like a fury ability. In an expansion focused on class fantasy, this is probably important
2. It needs to proc off dodge/parry. This is always part of what made the ability fun and powerful. Even if you change it to only auto attack dodge/parry. This needs to be part of the mechanic.
3. Arms plays wonderfully with a few artifact traits, it would be cool to see this have some small impact on gameplay besides just being a proc. Since you're giving up a gcd for CS resets, and costs rage, AND it's a talent. I think something as simple as your next slam/ms/execute will have an additional chance to trigger colossus smash. That seems to fit the theme of an ability called Overpower as well.
Heroic Strike
1. Similar to Overpower, with the new Arms rotation I'm not feeling like this has a place in the Arms toolkit. Heroic Strike is typically meant to generate a faster play style. That's not what arms is about. These two abilities would help truly separate the two specs from each other as well.
2. Make it do damage. Not this ridiculous stacking buff idea. Rampage is fun and all that but there's a world there where Heroic Strike can make sense even in conjunction with Rampage.
Heroic Strike - Deals X damage, off GCD. Rampage removes rage cost for 2 seconds. Critical Strikes will refresh enrage, but not activate it.
-It's currently tuned that while enraged you have a net gain in rage when using Heroic Strike/Raging Blow. So you're still going to have to use Rampage to dump rage. But can maintain the fast playstyle you wanted by choosing heroic strike.
**It should be tuned to be used above Rampage while enraged. The original alpha mechanic of it doing double damage while enraged was a fine way to do this.