Ah yes, missed the quick attack restriction for the second attack (but not for the first). OK, I have been using it correctly... except didn't realize the Battle Fury attack could choose a new target as well.
With [mwcard=FWQ04]Galvitar, Force Blade[/mwcard], I've done something similar to what's described for the Hydra: full action doublestrike (or Sweeping if prefered), then Battle Fury (from either my quick-cast or a Thoughtspore) into a quick attack with Piercing, then throw a [mwcard=FWQ01]Dancing Scimitar[/mwcard] for good measure. I never noticed that you could actually choose 4 different targets if you wanted to (e.g. choose "Sweeping" on the first Galvitar attack, then choose a different target for each of Battle Fury's swing and the Scimitar).