I agree completely. The current offensive benefits of Unyielding Sentinel are far too little. I don't think it quite has to match the all around good dps of Dreadnaught or Fury, but I think it should have better situational damage and should certainly have enough threat enhancers that even if it's doing less dps, it should be able to hold aggro if there is a situation where tanking is important.
I'm still a fan of offering extra damage or crit range and multiplier against intimidated targets for a short duration. It feels like it's in theme, has great synergy with smites and helps establish and maintain aggro after intimidating a boss or group of mobs.
The wiki lists intimidate with a 15 second cooldown, giving +50% threat for 6 seconds after a successful intimidate and +100% for 12 seconds if a shield is equipped. I'd make an enhancement or ability that also adds +1 threat range and multiplier during that duration. It's also a nice push for S&B fighting which needs a boost. Intimidating 10 or more mobs then cleaving through them would be quite fun.