"Added physical damage per N armour on shield" with "increased defences from equipped shield"

Not sure if this is a bug or working as intended (since it says "from shields" instead of "to shields"). Probably working as intended but wanted to verify in case it was a bug. The description is a bit vague so I could see it either way.

Shield skills take into account the shield's armor to determine the damage (resonating shield, shield charge, etc). X - Y Added physical damage per N armour on shield. I was thinking that "N% increased defences from equipped shield" would increase the damage (e.g. Towering Shield passive or found on some jewels). Seems this modifier only adds to the character's total armor rather than the shield's actual armor so there's no change to the attack damage of shield skills.

If this isn't a bug, I'd recommend changing it to work like this instead so shield skills could have more interesting ways of boosting damage.