Skirmisher Levies are only marginally better than peasant levies, with one regard: they have a ranged albeit inaccurate attack, whose rate of fire leaves much to be desired against more professional ranged units. Even Asian suicide soldiers will have a field day against these fellows once they get their hands on them, which is not very long once they encounter each other. Against buildings which normally have an armour bonus, skirmisher levies are thoroughly hopeless and thus cannot be relied upon on offence unless escorted by other stronger units. Still, unlike the more parochial Peasant Levy, Skirmisher Levies can be used to accompany troops on expeditions, making them far more useful as a component of your armies.