Once a footsoldier has been promoted to an Enforcer, they are no longer considered the punching bags of the Wickless Remains. But that doesn't mean that they won't haze new recruits the same way they were.
Frenzystone is effective on units with Strike affixes because the Strike is triggered for each attack, effectively doubling the Strike bonus under most circumstances.
As long as you can reliably reform or add additional burnout with spells to Paraffin Enforcer as he burns out, Wickstone is effective because it allows his Strike ability to apply to himself. It also allows you to comfortably place him before other Burnout units on the floor, so that the additional Rage is applied before their attacks.