I would say while WB has better condition-clears and stability, it's sticking power and reliable dmg are worse than herald.
Compare the two:
Herald: Unblockables, Super-speed, quickness, more vitality, Solid forms of both Soft and Hard-cc, incredible sticking power with easier-to-land front-loaded damage.
Willbender: Group-stability and condition clear. Almost no soft-cc and no hard-cc, no quickness, no unblockables, no super-speed, less health. It can do more damage than herald but it's much harder to land by comparison without super-speed, quickness or the cc's(soft and hard) necessary to stick. Also, the animations and cast-times for damage are much longer.
Compare Death Strike to Executioner's Calling: One is an instant port with fury to high damage with a 1/2 cast-time. Executioner's is pure melee with it taking 1 1/2 seconds to land ALL the hits since it's a 2-part attack.