Close quarters combat, in the game you hold R1 to cqc hold. and hold tighter after there
knocket out to kill. After youve held them you can either-stab the with s-scanner (enemy
locater, stab them with the syringe to knock them out fast or suppress nanomachine
activities (needed for vamp(spoiler)), or slit there throat. Or throw them down to the
ground.

I hope this helps :)

close corter combat dumb ***