I think what every paladin would love is for Shield Swipe to be exactly the same as it is now, but have a 3 or 4 x enmity modifier. 3.5x would be great - noticeably less overall than Halone, but would be slightly more threat per GCD than the average of the halone combo.

That way, pressing Shield Swipe would be threat-positive at all times over doing a Halone Combo. That's the issue with Shield Swipe now. It procs fairly often but you're loathed to use it unless you have a threat lead. If you -wanted- to press Shield Swipe in any situation it was up, it would feel a lot better. The alternative is to pull it off the GCD and give it a cooldown but that feels like it would lose some of its uniqueness.