Focus less on actual armor and more on keeping the enemy at a distance.  Ranged weaponry is your friend.  In most role-playing and computer games, the sling is almost always seen as a sub-optimal weapon.  In actual use, using prepared shot (not just stone, but specially made of metal or ceramic), they can be quite deadly.  If the Lokk are also physically weak in addition to being frail, then the crossbow may be ideal, if using cranks to set them.

Speaking of friends, heavily armored trained warbeasts (rhinos, elephants, etc) can be used to directly engage while the Lokk stay back.  This does assume a more fantasy element in which such warbeasts can be controlled and directed better than in the real world.

Light cavalry (lightly armored, fast moving, armed with bows, slings or javelins), will allow the Lokk to strike and not remain in place to be smacked with blunt force.  Heavy cavalry would not be a good option, as that is all about dealing (and often receiving) heavy strikes and direct conflict.

Formation fighting will be vital for when combat does get close.  Shield-walls and Turtles equipped with spears and pole-arms will keep direct "hand-to-hand" combat to a minimum.  These will also be the counter to any heavy cavalry used by the Lotl.

Of course, as the Emperor has declared that the solution is to wear armor, it will be the job of his advisors to not have their heads removed while attempting to let the Emperor know that his solution is not practical.