The Black Powder Bomb is a thrown clay pot of Mongol powder that explodes on impact, damaging and staggering everyone in a wide area. It is the tool for breaking up a crowd before you go in with the sword.
Select Throw with L2 and left on the d-pad, equip the bomb with L2 and Circle, then throw with L2 and R2. Anyone in the radius is staggered, which buys time to pick off the weakest.
Concussive Blast is the big one: knocked-down enemies are open to a finishing strike before they stand. Add shrapnel for a wider area, and pair the Charm of Incineration for burn damage on top.