Reading it more and talking to others... it's definitely the second case. Comes down to this specific line: Make a secondary attack,
which has the fear keyword. Basically, it becomes a fear attack only (having a burst 3 range is pretty much a dead give away). It's a straight Con attack.
If it was the 1st case and you basically get
Invigorating,
Martial,
Weapon & Fear... damn, that'll definitely be broken. 1st off, Hammer Rythm will be insane. 2nd, you're almost (99%) guaranteed to hit getting THP. 3rd, there's a possibility that it will
stack if you hit multiple targets with the secondary attack.