Only 3 units for Illian? Hehe, as an Illianer die-hard, I gotta help with that.

Alright, so I assume it's widely accepted that Illian is basically Greece and the like. After all the Illianer Companions are exactly, if I remember right, like Alexander's Companions. So right there, their moral/discipline/elite/armor, after all they've turned the battle many times in Randland, should be off the scale. Now, they also have armies a bit of heavy horses. So right there.

Also, if I remember correctly, Alexander had an elite unit of foot soldiers called the Hypaspits, who also were elite, very disciplined, and very good. So, might give Illian an unit like that.

Also, might make an Agrianian-type unit who're light, crack javelliners. Alexander made heavy use of them.

Also, the Macedonian infantry was very versatile if I remember well.

Also, since the Council often fought for power with the King, in a totally peaceful way, it'd be unthinkable for them not to have several units that match the power, skill and prestige of those that are for the king.