They have very thick armors, they can deal a lot of damage, have increased leadership and wield shields as well. This makes them one of the most vulnerable (and useless) units in the game. They cast aside their shields to wield two-handed weapons, which increase their damage, but at the same time lowers their armor to a measly 15 points. Those units should be used only during the first couple dozen of turns, until you unlock access to Chaos Warriors and Chosen.
They have shields and average damage, but they lack armor.
Armies of Chaos have access to the following melee infantry units: