In general, imbuing weapons gives them an increase to their base damage but a decrease to their scaling. However, because scaling is next to useless in Dark Souls 2 as well as imbuined weapons being enchantable there is no drawback currently to imbuing your weapons. I would suggest getting base stats needed to use the weapon you want, imbuing it with dark, and then enchanting it with Resonant Weapon for massive amounts of damage.