A few thoughts on Warrior/Marauder skills:

Inner Beast: This skill is well-defined and designed for a reactive tank. A solid burst damage + heal that spends the 15% increased healing received. The other Warrior skills should feel this good when you spend your Wrath stacks and at the same time make you think before just using a skill whenever its ready.

Defiance: Defiance feels like a homogenization of the two tank classes. The paradigm for tanks now are aggro-holding meleers who hit like a wet noodle. This doesnt need to be the case for EVERY tank out there. Let's go with removing the damage penalty for Defiance. Yes, the WAR will hit harder, but no it cannot/will replace a pure dps. The dps can dedicate their stats towards doing damage. A tanking WAR would have to split their stats to more survivability and enmity generation stats. They'd just have to adjust the enmity generated by Defiance to offset this change.

As a consequence to removing the damage penalty, Unchained would have to be scrapped/reworked to something different.

A smaller change to Defiance would be to allow Overpower to generate stacks of Wrath in certain conditions. Seems silly relying on single-target abilities to perform an AOE Wrath spender, Steel Cyclone. When Overpower hits at least 3 targets, it should generate 1 Wrath. The cost of Overpower would prevent using this tactic for too long.

Steel Cyclone: This feels like it needs only a minor tweak to get it over the hill. A 25-50 potency boost perhaps?

Mercy Stroke: Mercy Stroke with Defiance up is so underwhelming. It does not justify having to wait for the target to be at 20% and the damage penalty hurts its chance to score the heal. Even with 60s enhanced cooldown, you rarely get a chance to use this skill twice in a fight and that means you'll only get the heal off once. Please have Mercy Stroke ignore Defiance.