Yeah that's a nice vulnerable damage roll, I have like 4 copies of this unique all up but never used it because I always had fresh non-uniques with high crit damage and vulnerable damage when they dropped. I'd say the one that makes rupture a blood pool is cooler, but this weapon is better currently because vulnerable damage (will probs be patched). It's hard to fit any weapon mastery skill into my build tho tbh on the basis that

1. Multiple basic skills are essential for weapon switch procs
2. Rallying cry is essential
3. Brawling skills like Leap, War Cry or Kick offer better utility with the right aspects