Tactical Officers can be recruited by spending Rank Points. 1 Tactical Officer will increase your attack by 1 point. Each Rank Point spent will recruit 2 Tactical Officers. So spending a full levels worth of rank points can hire 10 Tactical Officers (5 Rank points x 2 = 10), increasing your attack by 10.
Tactical Officers are included in your ship's crew that will help you in raiding enemy ships, and also help defend your ship from enemy raids.