I recently purchased some mercenary slots, and made some heroes. What I can't understand is that the game says that their armor is "3-60 (depends on level)". It was my understanding that all mercenary heroes, as they are created at Lv 20, had an armor of 60. Is this not the case?
That message is standard for all heroes. They all have that. It's redundant for the "(depends on level)" message to appear for mercenaries because, as you pointed out, they start at level 20 and will therefore always have the max armor for their profession (60 for casters, 70 for assassin/ranger/derv, 80 for warrior/paragon). Anet either didn't think to remove it or didn't think it was worth the effort to do so.