I'm not sure why we are all competing against eachother when we should be working together. Nerfing WAR is a good point for tank balance if the majority of the other tank's problem weren't because of their own class designs rather than comparisons between the tank classes. Apart from DPS, PLD's and DRK's would still suffer from TP problems and mitigation issues, nerfing WAR's in that area just adds them to the angry mob.

To OP's opening post:
1. Along with putting WAR's pretty much next to PLD or under DPS in OT and MT stance would also greatly slow down the pace of the class as well as the uptime of Inner Beast and Fell Cleave, the former making it's average uptime much lower than Rampart and Shadowskin and the latter essentially halving the DPS contribution of Fell cleave which was roughly 20-30% of a WAR's total DPS. You'd also break a WAR's Triple FC Berserk combo and that alone will stir an uproar.
2. At 200 potency it would suffer the current Shield Swipe dilemna in which people wouldn't use it because it'd be a DPS loss. Sure the Mitigation is great but it frankly only works when you have a Target and is on the GCD which can greatly screw you over if you miss time it. The self heal is a boon and Inner Beast more or less defines WAR's tanking kit.
3. 5% could work out, 10% is abit overkill unless you want to make DRK the lead of Damage for tanks.
4. I don't need to tell you that 1GCD of no damage > 8/12GCD's of reduced damage as well as a larger punishment if you happen to misjudge the incoming damage.
5. The TP from equilibrium actually just makes WAR's AoE sustain more plausible and being the Damage Tank it'd make sense for them to have good AoE sustain along with DRK's. This change won't really affect WAR ST as much since alot of their TP sustain is from Free GCD's through Fell Cleave/Inner Beast and Pacifications.
6. Lol I could already maintain aggro without Butcher's. This would just be a buff to muh DPS tanking shenanigans since I'd assume you'd just make SP better than BB in terms of potency making muh DPS tanking more viable. Idk mang. ¯\_(ツ)_/¯ The WAR could y'know, use his brain and use SP instead of screwing with enmity if its even a problem.

7?. I don't remember but the averages of Sentinel vs Vengeance in uptime and potency were somewhat similiar. You'd just make Vengeance inferior to Sentinel. LolShadowWall. Thrill of Battle is pretty crappy on its own and doesn't deserve the extended cooldown for what it does. You'd just screw over the timing with Convalescence.

8. Idk 15% might be fine.

Balance is great.

But balancing to garbage tier is not fun. Everyone wants to have fun!

A reasonable nerf I'd like to see however would be the redesign of Storm's Path into something else and returning the effect to BRD and MCH. That way WAR would be brought for more damage and the other two for more mitigations. Idk just spitballing.