James Reed's 3-pointer gave American its first since lead since early on, 40-39, with 6:57 to go. Delante Jones added a basket but Wagner scored the next 10 points, including four each by Carey and Corey Henson to lead 49-42 with 27 seconds left.
All four of victories for the Seahawks (4-2) have come at home.
Henson scored 14 points for Wagner and Dwaun Anderson added 11. It was Anderson's sixth consecutive double-figure game.
Delante Jones scored 20 points, a career high for the freshman. The Eagles (2-6) committed 21 turnovers, which Wagner turned into 23 points.