Since the Harondor Archers in Mordor have poison arrows as an upgrade instead of fire arrows why not just make the Harondor Archers used in Mordor and Haradwaith the same unit. This Harondor Archer would be able to upgrade it's self with fire arrows, but also use an ability to fire poison arrows (just like the Moria Goblin Archers).
Also I'd suggest mention in the upgrade texts exactly what they do, for example: "Fire to Fire Arrows to increase this hordes damage towards structures by +50% and units by +25%"
Edited by saruman_the_wise, 01 May 2017 - 01:10 PM.