Probably a bad idea. Armor weighs units down, and the game doesn't care how strong you are, 20 ton armor weighs you down to a slug's crawl regardless.
You're better off making that "Armor" a part of Armok's own body, like a shell or an exoskeleton, although just making him out of solid Duronium, and making him rediculously thick and dense is probably a better bet.
Better idea, make him able to fly and make both his skin and armour superthick, and make him superfast.
That's my point - actual armor will slow you down, regardless of how strong he is, and you will move like a slug. My dwarves are SPEED:0, which is as fast as this game lets you be, and they still move like they have SPEED:1,000,000 when they are wearing 20-ton armor, even if they, themselves, weigh 600 tons, all of it muscle.
If you want armor, make it a part of his body, where it doesn't count against your speed, rather than having him "wear" anything, which will greatly slow you down. My dwarves easily move 1/10th their SPEED:0 speed just because they are wearing pants and socks, much less armor.
Flying is perfectly fine, though.
In other news, my wall is going fine, but as I get closer to one of the major entry points of the clowns, I get interrupted more and more often by demons flying out of the holes I'm trying to seal.
Fortunately, since I ordered all my dwarves into "militia" that are permanently inactive, but which have a "uniform" of "nakey time", they can easily outrun the clowns, and don't do stupid things like dodge into the red asterisks.
The actual hole is at 4 z up, so I'm building all four levels simultaniously (I.E. I've accomplished more than it looks), although the walls are kind of spotty, since I keep adding more stairs extensions.
edit: Also, if anyone else wants to pull this stunt, besides "don't have masive littersizes that kill your FPS" or "don't bring more than one or two beast types", if you want to wall HFS in, you should probably also
embark on a friggin 2x2 site at most. I don't know why I didn't.