User blog comment:TW6464/Reckoning DLC Leak. Via REDDIT/@comment-78.8.137.22-20130129225828/@comment-24174486-20130130001653

Marksman + Tactical Scan = huge increase in weapon damage. You can also go Tactical Scan + (Rank 6 Tech Vulnerability) Sabotage to make the Quarian Marksman an excellent but situational debuffer—though you won't regret it if you've got at least two tech-power-focused squadmates to take advantage of Tech Vulnerability.