Standoff Streak extends a Standoff so a second enemy charges in after the first falls. Time your strike as he swings and he dies too, for two kills before the fight starts.
Win the first draw, then wait for the next enemy's swing and strike.
Buy it with Technique Points after Standoff.
Archery
Aim and fire a bow.
Assassination
Kill an unaware enemy with a quiet stealth attack from behind or above.
Chain Assassination
Assassinate two nearby unaware enemies one after the other.
Chain Assassination Master
Chain up to three assassinations in quick succession.