So, Iron Heart Surge gets a lot of love and a lot of hate. It's like marmite in its own way, except the Americans are aware of it, it's no good on toast and the Australians don't have their own (better) version, but anyway.
I propose the following fix:
Iron Heart Surge
1 Immediate Action
The initiator may re-roll a failed save with a +2 bonus. The initiator must accept the new result, even if it is lower. You also surge with confidence and vengeance against your enemies, gaining a +2 morale bonus on attack rolls until the end of your next turn.
I feel that that this captures the original intent: Any effect that would cause Conan to yell "CROM" and flex his mighty thews (and whoever made that comment originally, please step foward and recieve your cookie) and thus end what ever was causing him to have to flex his thews and yell "Crom", can be dealt with with this effect. In effect, this is a big red button labeled "no" and can be used as such.
Benefits of this: clearer as to what it does. Fail a save against charm? Initiate this maneuvre. You can, because it's immediate. Turned to stone? Initiate this maneuvre. Step inside an AMF? No, you can't as it does not allow a save. Warmed by the gentle rays of the sun? Sorry, you'll have to tan and burn with the rest of us.
Weaknesses: No good against things that do not allow a save and yet still have a duration, though I can't think of any off the top of my head.
Diliberations, criticisms and so on welcome.