I don't think I've seen a dev response to this anywhere, but when you try to equip the skill pierce via macro it does not equip. No matter how you spell it the skill will not equip via macro.
I have read this is because there was a Fencer skill called Pierce so they disabled it from working with macros to avoid confusion. My suggestion is to rename the skill Piercing Thrust. It's a pain to remember to go in and equip this skill when changing classes.
Please fix this if possible, ty.