In massive armies finding individual heroes/units is difficult so I think an option to make them alphabetical order or just have them be that by default. You may have to move the number of units after the unit name to make this easier.
Also to make using abilities easier would be when you click on a unit to use the ability have their picture/ ability button pop out on the side instead of having to scroll up to find it.
Last one I can think of right now is the ability to unmerge unit stacks unless you feel this would be unbalanced or is part of the risk vs. reward part of merging.
Obviously add any suggestions you also have for blight here as well