There are no 'double' or 'third' attack skills here.  Instead, there is a
single 'multiple attacks' skill.  This skill can be best learned by warriors
and thieves, and is usually acquired gradually.

The skill of multiple attacks increases the number of average attacks you make
per round.  In addition to training to get higher attacks, there are also
certain pieces of equipment that can boost your number of attacks.

Higher attacks are good, as it will give you a much higher probability of
attacking during combat.