Question about the Disciple of the Sword feat

The feat is very well written, and very specific, but there is one thing that irks me about it:

Prerequisites: Cleric or Inquisitor level 4th, Weapon Focus (Longsword), Worshipper of Iomedae.

Neither of these classes get feats at 4th level; so... why does it have 4th level as a prerequisite?