The fix for this seems very easy to me.

Add a slight raise to the enmity cap that only the Paladin can hit, make it merit based, then make it a 1% enmity cap with each merit point, allowing it to hit up to 5% above the enmity cap that other classes can hit.

Make this additional enmity cap decrease enmity at 2x the rate of normal enmity, with nothing that can effect its rate of decrease. As long as the Paladin is dealing damage at a slightly significant rate, they should be able to hold it above that additional cap.

"Volatile Enmity"

Alternatively, PLDs could just spam Flash and Provoke.