Technically you can not dual-wield in Conan Exiles. However, some weapons give the appearance of dual wielding. Daggers and some end-game axes, while considered two-handed weapons, are wielded in both hands of your character. You can also use thrown weapons, like javelins and throwing axes in your off-hand. You can not, however, use one-handed weapons in your off-hand. There have been talks of adding this feature down the road, but the game was not initially built to incorporate dual-wielding.