I discovered this rare melee moveset when playing Days Gone v1.00 on PS4 Pro (i.e. the disc with no updates or patches). I believe it happened after I destroyed a melee weapon against an enemy; normally Deacon automatically switches to his boot knife, but he didn't this time, resulting in this video.
Version of Days Gone: 1.00
Console: PS4 Pro
Console version: 10.01
Twitter: / shrev64