Quote: "..without armor to avoid randomness..."
isnt your weapon damaging between the highest possible and half of it, randomly ? (without an armor). wpf counts too and the duration of your swing, so when the end of the swing gots the enemy maybe it does minimal damage, when too early, it bounces off..
I dunno what is your test environment, but try with level 1 characters, read about what armor exactly does, and try to find a composition, when two cases are possible: 1 damage or 0 damage. idk its possible or not, but I would check it.