Maintenance for the week of December 23:
· [COMPLETE] NA megaservers for maintenance – December 23, 4:00AM EST (9:00 UTC) - 9:00AM EST (14:00 UTC)
· [COMPLETE] EU megaservers for maintenance – December 23, 9:00 UTC (4:00AM EST) - 14:00 UTC (9:00AM EST)
You have to have two weapons equipped or a one hand and shield to use the skills, but any skill on your bar will level up whether or not you can use it when you gain exp.
So you could level dual wield skills or one hand and shield if you put them on your bar, but you couldn't use them unless you equipped a second weapon or a weapon and shield.