Like the forsworn themselves. Duel wielding is more like a berserker I think. Not caring what happens to you. Skirmishers are hit it and run. Making sure they get out of there is top priority. SO, a sword and a light shield and light armor.
But skirmishing is more mentality than anything
Berserkers used a variety of weapons (not just dual-wield - you may be using the AD&D reference). In any case, berserkers are a type of skirmisher. The function of a skirmisher was to use hit and run tactics to inflict casualties and disrupt the enemy. Then during this chaos, the 'regular' units (if present) would engage the enemy.
I agree with most here. Skirmishers were light and mobile, and in addition to 'hit-and-run' tactics, could also serve reconnaissance duty. They often carried ranged weapons (javelins, short bows) in addition to their melee choice. They would often be part of a larger unit, to disrupt the enemy before the battle, and then either retreat or engage the enemy, depending on the circumstances, when the main units hit.
By the way, Vix the Loremaster, has (or will soon have) an advanced degree in history with an emphasis (I think) in warfare. He is very knowledgeable on the subject of warfare, weapons, etc., and can definitely tell us more.