This needs to be changed I don't know when it happened but the ability now says
This is a passive ability; this ability dose not need to be activated
Requirements: level 59 Archery Mastery at level 1
"This ability allows you to strike an enemy on the head inflicting massive damage when using a bow. Each rank increases the level allowable by this ability to 1 below the required level to acquire this ability."
So with the first level of this ability you can hit level 58 mobs