perhaps you should read some tutorials first. Dont take it personally, but it seems you are rather unexperienced with the world editor. look in the tutorial section, there are many fine basic tutorials.
To change the armor type you should go to the units fields "Combat"
Then find the line armor type. The hero to unit is by finding the field "Stats"
In the ability and make the changes you want you have two fields to edit
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.