Game mechanics question (0 melee damage arrows)

I was thinking about Cho Ko Nu arrows and how they do 0 melee damage per arrow and how this affects rams (due to rams -3 melee armor) but not much of anything else. Is it possible to have a unique tech change the damage done by arrows to add that 0 melee damage?

So, for example, could you change Boiling Oil to add 0 melee damage to each castle arrow (and extra arrow) for Persians after it is researched? If so, would these arrows only do extra damage to units with less than 0 melee armor like rams?

I don't know anything about programming this game or fully understand how the different armor classes/attributes work. I am just trying to understand.

Thanks.