A "pincer" maneuver involves a force splitting into two and attacking the enemy from both sides, thus a "half pincer" logically means the force attacks the enemy from only one side.
BA - "This ain't much of a plan, Hannibal."
Hannibal - "Are you kidding? It's a classic! It's your half pincer movement inside a guarded perimeter. Tried and true, BA!"
Mrs. Doubtfire "ooh very nice dear!"
Macaulay "please let me go home now."