I haven't. The closest I saw when looking for you was setting the Hero's agility to a higher number, which would indeed increase the armor. However, that would also increase attack speed, and I don't know/think you really want that too. What you CAN do, however, is create an ability that raises armor, like using the Inner Fire ability. You could give it to a dummy unit and have the dummy cast it on the whatever you need it cast on.
However, I believe dummy units require WEU. Not sure though.
-Edit-
On second thought, you may be able to do this without WEU if you do something like:
E: <Whatever you need it to be>
C: <Same>
A: Create 1 <Dummy unit> for <Neutral Passive, or something> at <Position of the unit it's going to be cast on, or something like that...>
Unit - Issue (last created unit) to cast <version of inner fire> on <whatever you need it to be cast on...>
It would be a little...No, really complex, but if you can't use WEU, like I couldn't (without it crashing when I tried to save...) then that's one way to get around it.