Echoing Weapon

You channel energy into the target weapon, and the air around it faintly hums each time it strikes a blow, as the impact is absorbed into the weapon. If a creature is wielding the weapon at the end of its turn, the weapon discharges a burst of sound targeting one creature adjacent to the wielder. The sonic damage dealt is equal to the number of successful Strikes with the target weapon that the wielder made that turn (to a maximum of 4 sonic damage if the wielder hits with four Strikes).

1: rank ÷ 2, rounded up sonic, 2: (rank ÷ 2, rounded up) × 2 sonic, 3: (rank ÷ 2, rounded up) × 3 sonic, 4: (rank ÷ 2, rounded up) × 4 sonic