I'm trying to do the final upgrade for the Longbow of Vengeance, which requires me to Shadow Strike Kill an Online Vendetta target. But every time I get them low enough to Shadow Strike Kill the target gets a "last chance" cut-scene and when I kill him it doesn't count as a Shadow Strike Kill.
How am I supposed to finish this upgrade? How can I actually get a lethal Shadow Strike on an Online Vendetta target?
EDIT: Last night I was able to get an insta-kill on a Vendetta target with Shadow Strike but didn't get the credit even though I had the bow equipped.
I was fighting a Vendetta Captain. He didn't have any Terrified By weaknesses or Dazed By weaknesses. However, when you poison a target, they have a few moments wherein they are incapacitated as they vomit and such. I did a Shadow Strike against him while he was vomiting and it did the instant-kill Decapitation Shadow Strike animation, said he was "Decapitated", but then I didn't get the credit on my Vendetta Bow. :(
EDIT 2: I finally found a target that could be Terrified, weakened him, Terrified him, and I did eleven Shadow Strike Kill hits on him... but then he still just did the final animation and I didn't get credit.
How the heck am I supposed to complete this upgrade?
I captured the whole thing this time: