Bug? No damage overflow against armoured enemies?

[Jerry]

Using the Bat Bow, I kill 1 dark hornet per arrow. After aquiring the Falcon Eye upgrade, I still kill 1 dark hornet per arrow. I would have assumed, it should be 2 by then. According to the 4.7 patch notes, "[Armoured enemies] will take damage from your arrows but they won't pass through them until Armored HP is depleted.", so that sounds like once their armoured HP are depleted, the arrows should pass through them.

[RAD-82]

No bug, but I'm having a hard time trying to explain it, so I won't. Maybe someone with better communication skills can come along and explain it.

Edit: Maybe I'll try again. If arrow hit armor, then destroy arrow, else arrow passes through. The amount of armor is irrelevant.

[Jerry]

That can't be right, that would make armoured enemies invincible, if your arrows are not strong enough to destroy the armour in one hit.
The patch note clearly refers to the enemy, not the armour, which in my eyes would mean, that the arrow strength is reduced by the enemy life points.

[RAD-82]

Why would they be invincible? They still do damage when hitting the armor.

I am currently in the desert with Metal Scorpions. They appear to have 5 HP and 5 armour HP. My bow does 4 damage. First arrow hits an armoured enemy and is destroyed, leaving the scorpions with 5 HP and 1 armour HP. Second arrow hits an armoured enemy and is destroyed, leaving the scorpions with 2 HP and 0 armour HP. Third arrow hits and passes through since there is no armour left, killing the scorpion after it suffered a total 10 damage.

Dark Hornets have 1 HP and 1 armour HP. First arrow hits an armoured enemy and is destroyed, and the Dark Hornet is killed after suffering a total of 2 damage.

As far as I know, the game doesn't have any mechanics for reducing the strength of the arrow and overflowing excessive damage done against armour, although I also haven't seen any of the new divinities either, so I don't know if such a mechanic could be hidden there.