Ive been tought by games that a successfull execute finisher will reset my abilities cooldown.
I think this would make Execute more viable and spice things up to go for this single target GA builds as well as increase its flavor value.
(Lookin at you Darius from LoL or Axe from Dota :D)
Could be implemented within the ability and/or as armor perks or in the perk tree. You could also change it from AoE to Single target for balance reason.
An optional speedboost as escape or chase mechanism on successful execution would be more interesting than the heal.