It was the first time the NAIA school had defeated its cross-town rival in three tries.
Blanco, who had 12 points in the first half, was scoreless in the second until he took over in the final minutes.
Incarnate Word's Kyle Hittle, who finished with 29 points, made two free throws with 1:58 left to take a 95-94 lead. Blanco answered with a 3-pointer and drove for a layup with 35 seconds left for the final score. Hittle was fouled with :03 left missed both free throws
Olajuwan Garner was 6 of 12 from the floor for 17 points and Kellen Sweetwyne added 12 for the Saints.
Jontrell Walker added 28 points for Incarnate Word (3-5).