Since they obviously want our abilities to function differently. How about adding a penalty to Scourge that Reprisal had, and making Reprisal a bit different and unique.
Reprisal:
Delivers an attack with a potency of 210.
Cool-down: 30, 15 with the trait.
Instant Cast, no GCD. No longer requires a parry.
Scourge:
Delivers an attack with a potency of 220.
Damage over time: 40, lasts 24 seconds.
TP cost: 20, however can only be used after a parry.
Cool-down: 15 seconds. Takes a GCD, does not break combo chains.