Most tales of the dwarven Legion of the Dead are likely minstrels' fabrications, but the trail of darkspawn corpses that the Legion leaves behind proves the efficacy of their training. Legionnaire scouts often travel ahead of their companions, and have consequently become renowned for unusual hardiness, able to survive battles that would kill any other rogue.
This specialization is only available if you have the Dragon Age: Origins - Awakening expansion pack installed. It also requires a minimum character level of 20. After acquiring the specialization, the character will gain access to four new talents
and be granted +2 dexterity and a +1 damage bonus per hit.
How to Unlock:
The specialization is made available by using the Manual: Legionnaire Scout